Terrain

This entry contains a brief description of the topography.

• Afghanistan

  mostly rugged mountains; plains in north and southwest

• Albania

  mostly mountains and hills; small plains along coast

• Algeria

  mostly high plateau and desert; Atlas Mountains in the far north and Hoggar Mountains in the south; narrow, discontinuous coastal plain

• American Samoa

  five volcanic islands with rugged peaks and limited coastal plains, two coral atolls (Rose Atoll, Swains Island)

• Andorra

  rugged mountains dissected by narrow valleys

• Angola

  narrow coastal plain rises abruptly to vast interior plateau

• Anguilla

  flat and low-lying island of coral and limestone

• Antarctica

  about 98% thick continental ice sheet and 2% barren rock, with average elevations between 2,000 and 4,000 m; mountain ranges up to nearly 5,000 m; ice-free coastal areas include parts of southern Victoria Land, Wilkes Land, the Antarctic Peninsula area, and parts of Ross Island on McMurdo Sound; glaciers form ice shelves along about half of the coastline, and floating ice shelves constitute 11% of the area of the continent

• Antigua and Barbuda

  mostly low-lying limestone and coral islands, with some higher volcanic areas

• Arctic Ocean

  central surface covered by a perennial drifting polar icepack that, on average, is about 3 m thick, although pressure ridges may be three times that thickness; the icepack is surrounded by open seas during the summer, but more than doubles in size during the winter and extends to the encircling landmasses; the ocean floor is about 50% continental shelf (highest percentage of any ocean) with the remainder a central basin interrupted by three submarine ridges (Alpha Cordillera, Nansen Cordillera, and Lomonosov Ridge)

  major surface currents: two major, slow-moving, wind-driven currents (drift streams) dominate: a clockwise drift pattern in the Beaufort Gyre in the western part of the Arctic Ocean and a nearly straight line Transpolar Drift Stream that moves eastward across the ocean from the New Siberian Islands (Russia) to the Fram Strait (between Greenland and Svalbard); sea ice that lies close to the center of the gyre can complete a 360 degree circle in about 2 years, while ice on the gyre periphery will complete the same circle in about 7-8 years; sea ice in the Transpolar Drift crosses the ocean in about 3 years

• Argentina

  rich plains of the Pampas in northern half, flat to rolling plateau of Patagonia in south, rugged Andes along western border

• Armenia

  Armenian Highland with mountains; little forest land; fast flowing rivers; good soil in Aras River valley

• Aruba

  flat with a few hills; scant vegetation

• Ashmore and Cartier Islands

  low with sand and coral

• Atlantic Ocean

  surface usually covered with sea ice in Labrador Sea, Denmark Strait, and coastal portions of the Baltic Sea from October to June; surface dominated by two large gyres (broad, circular systems of currents), one in the northern Atlantic and another in the southern Atlantic; the ocean floor is dominated by the Mid-Atlantic Ridge, a rugged north-south centerline for the entire Atlantic basin

  major surface currents: clockwise North Atlantic Gyre consists of the northward flowing, warm Gulf Stream in the west, the eastward flowing North Atlantic Current in the north, the southward flowing cold Canary Current in the east, and the westward flowing North Equatorial Current in the south; the counterclockwise South Atlantic Gyre composed of the southward flowing warm Brazil Current in the west, the eastward flowing South Atlantic Current in the south, the northward flowing cold Benguela Current in the east, and the westward flowing South Equatorial Current in the north

• Australia

  mostly low plateau with deserts; fertile plain in southeast

• Austria

  mostly mountains (Alps) in the west and south; mostly flat or gently sloping along the eastern and northern margins

• Azerbaijan

  large, flat Kur-Araz Ovaligi (Kura-Araks Lowland, much of it below sea level) with Great Caucasus Mountains to the north, Qarabag Yaylasi (Karabakh Upland) to the west; Baku lies on Abseron Yasaqligi (Apsheron Peninsula) that juts into Caspian Sea

• Bahamas, The

  long, flat coral formations with some low rounded hills

• Bahrain

  mostly low desert plain rising gently to low central escarpment

• Bangladesh

  mostly flat alluvial plain; hilly in southeast

• Barbados

  relatively flat; rises gently to central highland region

• Belarus

  generally flat with much marshland

• Belgium

  flat coastal plains in northwest, central rolling hills, rugged mountains of Ardennes Forest in southeast

• Belize

  flat, swampy coastal plain; low mountains in south

• Benin

  mostly flat to undulating plain; some hills and low mountains

• Bermuda

  low hills separated by fertile depressions

• Bhutan

  mostly mountainous with some fertile valleys and savanna

• Bolivia

  rugged Andes Mountains with a highland plateau (Altiplano), hills, lowland plains of the Amazon Basin

• Bosnia and Herzegovina

  mountains and valleys

• Botswana

  predominantly flat to gently rolling tableland; Kalahari Desert in southwest

• Bouvet Island

  volcanic; coast is mostly inaccessible

• Brazil

  mostly flat to rolling lowlands in north; some plains, hills, mountains, and narrow coastal belt

• British Indian Ocean Territory

  flat and low (most areas do not exceed two m in elevation)

• British Virgin Islands

  coral islands relatively flat; volcanic islands steep, hilly

• Brunei

  flat coastal plain rises to mountains in east; hilly lowland in west

• Bulgaria

  mostly mountains with lowlands in north and southeast

• Burkina Faso

  Mostly flat to dissected, undulating plains; hills in the west and southeast.  Occupies an extensive plateau with savanna that is grassy in the north and gradually gives way to sparse forests in the south. (2019)

• Burma

  central lowlands ringed by steep, rugged highlands

• Burundi

  hilly and mountainous, dropping to a plateau in east, some plains

• Cabo Verde

  steep, rugged, rocky, volcanic

• Cambodia

  mostly low, flat plains; mountains in southwest and north

• Cameroon

  diverse, with coastal plain in southwest, dissected plateau in center, mountains in west, plains in north

• Canada

  mostly plains with mountains in west, lowlands in southeast

• Cayman Islands

  low-lying limestone base surrounded by coral reefs

• Central African Republic

  vast, flat to rolling plateau; scattered hills in northeast and southwest

• Chad

  broad, arid plains in center, desert in north, mountains in northwest, lowlands in south

• Chile

  low coastal mountains, fertile central valley, rugged Andes in east

• China

  mostly mountains, high plateaus, deserts in west; plains, deltas, and hills in east

• Christmas Island

  steep cliffs along coast rise abruptly to central plateau

• Clipperton Island

  coral atoll

• Cocos (Keeling) Islands

  flat, low-lying coral atolls

• Colombia

  flat coastal lowlands, central highlands, high Andes Mountains, eastern lowland plains (Llanos)

• Comoros

  volcanic islands, interiors vary from steep mountains to low hills

• Congo, Democratic Republic of the

  vast central basin is a low-lying plateau; mountains in east

• Congo, Republic of the

  coastal plain, southern basin, central plateau, northern basin

• Cook Islands

  low coral atolls in north; volcanic, hilly islands in south

• Coral Sea Islands

  sand and coral reefs and islands (cays)

• Costa Rica

  coastal plains separated by rugged mountains including over 100 volcanic cones, of which several are major active volcanoes

• Cote d'Ivoire

  mostly flat to undulating plains; mountains in northwest

• Croatia

  geographically diverse; flat plains along Hungarian border, low mountains and highlands near Adriatic coastline and islands

• Cuba

  mostly flat to rolling plains, with rugged hills and mountains in the southeast

• Curacao

  generally low, hilly terrain

• Cyprus

  central plain with mountains to north and south; scattered but significant plains along southern coast

• Czechia

  Bohemia in the west consists of rolling plains, hills, and plateaus surrounded by low mountains; Moravia in the east consists of very hilly country

• Denmark

  low and flat to gently rolling plains

• Djibouti

  coastal plain and plateau separated by central mountains

• Dominica

  rugged mountains of volcanic origin

• Dominican Republic

  rugged highlands and mountains interspersed with fertile valleys

• Ecuador

  coastal plain (costa), inter-Andean central highlands (sierra), and flat to rolling eastern jungle (oriente)

• Egypt

  vast desert plateau interrupted by Nile valley and delta

• El Salvador

  mostly mountains with narrow coastal belt and central plateau

• Equatorial Guinea

  coastal plains rise to interior hills; islands are volcanic

• Eritrea

  dominated by extension of Ethiopian north-south trending highlands, descending on the east to a coastal desert plain, on the northwest to hilly terrain and on the southwest to flat-to-rolling plains

• Estonia

  marshy, lowlands; flat in the north, hilly in the south

• Eswatini

  mostly mountains and hills; some moderately sloping plains

• Ethiopia

  high plateau with central mountain range divided by Great Rift Valley

• European Union

  fairly flat along Baltic and Atlantic coasts; mountainous in the central and southern areas

• Falkland Islands (Islas Malvinas)

  rocky, hilly, mountainous with some boggy, undulating plains

• Faroe Islands

  rugged, rocky, some low peaks; cliffs along most of coast

• Fiji

  mostly mountains of volcanic origin

• Finland

  mostly low, flat to rolling plains interspersed with lakes and low hills

• France

  metropolitan France: mostly flat plains or gently rolling hills in north and west; remainder is mountainous, especially Pyrenees in south, Alps in east;

  French Guiana: low-lying coastal plains rising to hills and small mountains;

  Guadeloupe: Basse-Terre is volcanic in origin with interior mountains; Grande-Terre is low limestone formation; most of the seven other islands are volcanic in origin;

  Martinique: mountainous with indented coastline; dormant volcano;

  Mayotte: generally undulating, with deep ravines and ancient volcanic peaks;

  Reunion: mostly rugged and mountainous; fertile lowlands along coast

• French Polynesia

  mixture of rugged high islands and low islands with reefs

• French Southern and Antarctic Lands

  Ile Amsterdam (Ile Amsterdam et Ile Saint-Paul): a volcanic island with steep coastal cliffs; the center floor of the volcano is a large plateau;

  Ile Saint-Paul (Ile Amsterdam et Ile Saint-Paul): triangular in shape, the island is the top of a volcano, rocky with steep cliffs on the eastern side; has active thermal springs;

  Iles Crozet: a large archipelago formed from the Crozet Plateau is divided into two groups of islands;

  Iles Kerguelen: the interior of the large island of Ile Kerguelen is composed of high mountains, hills, valleys, and plains with peninsulas stretching off its coasts;

  Bassas da India (Iles Eparses): atoll, awash at high tide; shallow (15 m) lagoon;

  Europa Island, Glorioso Islands, Juan de Nova Island: low, flat, and sandy;

  Tromelin Island (Iles Eparses): low, flat, sandy; likely volcanic seamount

• Gabon

  narrow coastal plain; hilly interior; savanna in east and south

• Gambia, The

  flood plain of the Gambia River flanked by some low hills

• Gaza Strip

  flat to rolling, sand- and dune-covered coastal plain

• Georgia

  largely mountainous with Great Caucasus Mountains in the north and Lesser Caucasus Mountains in the south; Kolkhet'is Dablobi (Kolkhida Lowland) opens to the Black Sea in the west; Mtkvari River Basin in the east; fertile soils in river valley flood plains and foothills of Kolkhida Lowland

• Germany

  lowlands in north, uplands in center, Bavarian Alps in south

• Ghana

  mostly low plains with dissected plateau in south-central area

• Gibraltar

  a narrow coastal lowland borders the Rock of Gibraltar

• Greece

  mountainous with ranges extending into the sea as peninsulas or chains of islands

• Greenland

  flat to gradually sloping icecap covers all but a narrow, mountainous, barren, rocky coast

• Grenada

  volcanic in origin with central mountains

• Guam

  volcanic origin, surrounded by coral reefs; relatively flat coralline limestone plateau (source of most fresh water), with steep coastal cliffs and narrow coastal plains in north, low hills in center, mountains in south

• Guatemala

  two east-west trending mountain chains divide the country into three regions: the mountainous highlands, the Pacific coast south of mountains, and the vast northern Peten lowlands

• Guernsey

  mostly flat with low hills in southwest

• Guinea

  generally flat coastal plain, hilly to mountainous interior

• Guinea-Bissau

  mostly low-lying coastal plain with a deeply indented estuarine coastline rising to savanna in east; numerous off-shore islands including the Arquipelago Dos Bijagos consisting of 18 main islands and many small islets

• Guyana

  mostly rolling highlands; low coastal plain; savanna in south

• Haiti

  mostly rough and mountainous

• Heard Island and McDonald Islands

  Heard Island - 80% ice-covered, bleak and mountainous, dominated by a large massif (Big Ben) and an active volcano (Mawson Peak); McDonald Islands - small and rocky

• Holy See (Vatican City)

  urban; low hill

• Honduras

  mostly mountains in interior, narrow coastal plains

• Hong Kong

  hilly to mountainous with steep slopes; lowlands in north

• Hungary

  mostly flat to rolling plains; hills and low mountains on the Slovakian border

• Iceland

  mostly plateau interspersed with mountain peaks, icefields; coast deeply indented by bays and fiords

• India

  upland plain (Deccan Plateau) in south, flat to rolling plain along the Ganges, deserts in west, Himalayas in north

• Indian Ocean

  surface dominated by a major gyre (broad, circular system of currents) in the southern Indian Ocean and a unique reversal of surface currents in the northern Indian Ocean; ocean floor is dominated by the Mid-Indian Ocean Ridge and subdivided by the Southeast Indian Ocean Ridge, Southwest Indian Ocean Ridge, and Ninetyeast Ridge

  major surface currents: the counterclockwise Indian Ocean Gyre comprised of the southward flowing warm Agulhas and East Madagascar Currents in the west, the eastward flowing South Indian Current in the south, the northward flowing cold West Australian Current in the east, and the westward flowing South Equatorial Current in the north; a distinctive annual reversal of surface currents occurs in the northern Indian Ocean; low atmospheric pressure over southwest Asia from hot, rising, summer air results in the southwest monsoon and southwest-to-northeast winds and clockwise currents, while high pressure over northern Asia from cold, falling, winter air results in the northeast monsoon and northeast-to-southwest winds and counterclockwise currents

• Indonesia

  mostly coastal lowlands; larger islands have interior mountains

• Iran

  rugged, mountainous rim; high, central basin with deserts, mountains; small, discontinuous plains along both coasts

• Iraq

  mostly broad plains; reedy marshes along Iranian border in south with large flooded areas; mountains along borders with Iran and Turkey

• Ireland

  mostly flat to rolling interior plain surrounded by rugged hills and low mountains; sea cliffs on west coast

• Isle of Man

  hills in north and south bisected by central valley

• Israel

  Negev desert in the south; low coastal plain; central mountains; Jordan Rift Valley

• Italy

  mostly rugged and mountainous; some plains, coastal lowlands

• Jamaica

  mostly mountains, with narrow, discontinuous coastal plain

• Jan Mayen

  volcanic island, partly covered by glaciers

• Japan

  mostly rugged and mountainous

• Jersey

  gently rolling plain with low, rugged hills along north coast

• Jordan

  mostly arid desert plateau; a great north-south geological rift along the west of the country is the dominant topographical feature and includes the Jordan River Valley, the Dead Sea, and the Jordanian Highlands

• Kazakhstan

  vast flat steppe extending from the Volga in the west to the Altai Mountains in the east and from the plains of western Siberia in the north to oases and deserts of Central Asia in the south

• Kenya

  low plains rise to central highlands bisected by Great Rift Valley; fertile plateau in west

• Kiribati

  mostly low-lying coral atolls surrounded by extensive reefs

• Korea, North

  mostly hills and mountains separated by deep, narrow valleys; wide coastal plains in west, discontinuous in east

• Korea, South

  mostly hills and mountains; wide coastal plains in west and south

• Kosovo

  flat fluvial basin at an elevation of 400-700 m above sea level surrounded by several high mountain ranges with elevations of 2,000 to 2,500 m

• Kuwait

  flat to slightly undulating desert plain

• Kyrgyzstan

  peaks of the Tien Shan mountain range and associated valleys and basins encompass the entire country

• Laos

  mostly rugged mountains; some plains and plateaus

• Latvia

  low plain

• Lebanon

  narrow coastal plain; El Beqaa (Bekaa Valley) separates Lebanon and Anti-Lebanon Mountains

• Lesotho

  mostly highland with plateaus, hills, and mountains

• Liberia

  mostly flat to rolling coastal plains rising to rolling plateau and low mountains in northeast

• Libya

  mostly barren, flat to undulating plains, plateaus, depressions

• Liechtenstein

  mostly mountainous (Alps) with Rhine Valley in western third

• Lithuania

  lowland, many scattered small lakes, fertile soil

• Luxembourg

  mostly gently rolling uplands with broad, shallow valleys; uplands to slightly mountainous in the north; steep slope down to Moselle flood plain in the southeast

• Macau

  generally flat

• Madagascar

  narrow coastal plain, high plateau and mountains in center

• Malawi

  narrow elongated plateau with rolling plains, rounded hills, some mountains

• Malaysia

  coastal plains rising to hills and mountains

• Maldives

  flat, with white sandy beaches

• Mali

  mostly flat to rolling northern plains covered by sand; savanna in south, rugged hills in northeast

• Malta

  mostly low, rocky, flat to dissected plains; many coastal cliffs

• Marshall Islands

  low coral limestone and sand islands

• Mauritania

  mostly barren, flat plains of the Sahara; some central hills

• Mauritius

  small coastal plain rising to discontinuous mountains encircling central plateau

• Mexico

  high, rugged mountains; low coastal plains; high plateaus; desert

• Micronesia, Federated States of

  islands vary geologically from high mountainous islands to low, coral atolls; volcanic outcroppings on Pohnpei, Kosrae, and Chuuk

• Moldova

  rolling steppe, gradual slope south to Black Sea

• Monaco

  hilly, rugged, rocky

• Mongolia

  vast semidesert and desert plains, grassy steppe, mountains in west and southwest; Gobi Desert in south-central

• Montenegro

  highly indented coastline with narrow coastal plain backed by rugged high limestone mountains and plateaus

• Montserrat

  volcanic island, mostly mountainous, with small coastal lowland

• Morocco

  mountainous northern coast (Rif Mountains) and interior (Atlas Mountains) bordered by large plateaus with intermontane valleys, and fertile coastal plains; the south is mostly low, flat desert with large areas of rocky or sandy surfaces 

• Mozambique

  mostly coastal lowlands, uplands in center, high plateaus in northwest, mountains in west

• Namibia

  mostly high plateau; Namib Desert along coast; Kalahari Desert in east

• Nauru

  sandy beach rises to fertile ring around raised coral reefs with phosphate plateau in center

• Navassa Island

  raised flat to undulating coral and limestone plateau; ringed by vertical white cliffs (9 to 15 m high)

• Nepal

  Tarai or flat river plain of the Ganges in south; central hill region with rugged Himalayas in north

• Netherlands

  mostly coastal lowland and reclaimed land (polders); some hills in southeast

• New Caledonia

  coastal plains with interior mountains

• New Zealand

  predominately mountainous with large coastal plains

• Nicaragua

  extensive Atlantic coastal plains rising to central interior mountains; narrow Pacific coastal plain interrupted by volcanoes

• Niger

  predominately desert plains and sand dunes; flat to rolling plains in south; hills in north

• Nigeria

  southern lowlands merge into central hills and plateaus; mountains in southeast, plains in north

• Niue

  steep limestone cliffs along coast, central plateau

• Norfolk Island

  volcanic island with mostly rolling plains

• North Macedonia

  mountainous with deep basins and valleys; three large lakes, each divided by a frontier line; country bisected by the Vardar River

• Northern Mariana Islands

  the southern islands in this north-south trending archipelago are limestone, with fringing coral reefs; the northern islands are volcanic, with active volcanoes on several islands

• Norway

  glaciated; mostly high plateaus and rugged mountains broken by fertile valleys; small, scattered plains; coastline deeply indented by fjords; arctic tundra in north

• Oman

  central desert plain, rugged mountains in north and south

• Pacific Ocean

  surface dominated by two large gyres (broad, circular systems of currents), one in the northern Pacific and another in the southern Pacific; in the northern Pacific, sea ice forms in the Bering Sea and Sea of Okhotsk in winter; in the southern Pacific, sea ice from Antarctica reaches its northernmost extent in October; the ocean floor in the eastern Pacific is dominated by the East Pacific Rise, while the western Pacific is dissected by deep trenches, including the Mariana Trench, which is the world's deepest at 10,924 m

  major surface currents: clockwise North Pacific Gyre formed by the warm northward flowing Kuroshio Current in the west, the eastward flowing North Pacific Current in the north, the southward flowing cold California Current in the east, and the westward flowing North Equatorial Current in the south; the counterclockwise South Pacific Gyre composed of the southward flowing warm East Australian Current in the west, the eastward flowing South Pacific Current in the south, the northward flowing cold Peru (Humbolt) Current in the east, and the westward flowing South Equatorial Current in the north

• Pakistan

  divided into three major geographic areas: the northern highlands, the Indus River plain in the center and east, and the Balochistan Plateau in the south and west

• Palau

  varying topography from the high, mountainous main island of Babelthuap to low, coral islands usually fringed by large barrier reefs

• Panama

  interior mostly steep, rugged mountains with dissected, upland plains; coastal plains with rolling hills

• Papua New Guinea

  mostly mountains with coastal lowlands and rolling foothills

• Paracel Islands

  mostly low and flat

• Paraguay

  grassy plains and wooded hills east of Rio Paraguay; Gran Chaco region west of Rio Paraguay mostly low, marshy plain near the river, and dry forest and thorny scrub elsewhere

• Peru

  western coastal plain (costa), high and rugged Andes in center (sierra), eastern lowland jungle of Amazon Basin (selva)

• Philippines

  mostly mountains with narrow to extensive coastal lowlands

• Pitcairn Islands

  rugged volcanic formation; rocky coastline with cliffs

• Poland

  mostly flat plain; mountains along southern border

• Portugal

  the west-flowing Tagus River divides the country: the north is mountainous toward the interior, while the south is characterized by rolling plains

• Puerto Rico

  mostly mountains with coastal plain in north; precipitous mountains to the sea on west coast; sandy beaches along most coastal areas

• Qatar

  mostly flat and barren desert

• Romania

  central Transylvanian Basin is separated from the Moldavian Plateau on the east by the Eastern Carpathian Mountains and separated from the Walachian Plain on the south by the Transylvanian Alps

• Russia

  broad plain with low hills west of Urals; vast coniferous forest and tundra in Siberia; uplands and mountains along southern border regions

• Rwanda

  mostly grassy uplands and hills; relief is mountainous with altitude declining from west to east

• Saint Barthelemy

  hilly, almost completely surrounded by shallow-water reefs, with plentiful beaches

• Saint Helena, Ascension, and Tristan da Cunha

  the islands of this group are of volcanic origin associated with the Atlantic Mid-Ocean Ridge

  Saint Helena: rugged, volcanic; small scattered plateaus and plains;

  Ascension: surface covered by lava flows and cinder cones of 44 dormant volcanoes; terrain rises to the east;

  Tristan da Cunha: sheer cliffs line the coastline of the nearly circular island; the flanks of the central volcanic peak are deeply dissected; narrow coastal plain lies between The Peak and the coastal cliffs

• Saint Kitts and Nevis

  volcanic with mountainous interiors

• Saint Lucia

  volcanic and mountainous with broad, fertile valleys

• Saint Pierre and Miquelon

  mostly barren rock

• Saint Vincent and the Grenadines

  volcanic, mountainous

• Samoa

  two main islands (Savaii, Upolu) and several smaller islands and uninhabited islets; narrow coastal plain with volcanic, rugged mountains in interior

• San Marino

  rugged mountains

• Sao Tome and Principe

  volcanic, mountainous

• Saudi Arabia

  mostly sandy desert

• Senegal

  generally low, rolling, plains rising to foothills in southeast

• Serbia

  extremely varied; to the north, rich fertile plains; to the east, limestone ranges and basins; to the southeast, ancient mountains and hills

• Seychelles

  Mahe Group is volcanic with a narrow coastal strip and rocky, hilly interior; others are coral, flat, elevated reefs

• Sierra Leone

  coastal belt of mangrove swamps, wooded hill country, upland plateau, mountains in east

• Singapore

  lowlying, gently undulating central plateau

• Sint Maarten

  low, hilly terrain, volcanic origin

• Slovakia

  rugged mountains in the central and northern part and lowlands in the south

• Slovenia

  a short southwestern coastal strip of Karst topography on the Adriatic; an alpine mountain region lies adjacent to Italy and Austria in the north; mixed mountains and valleys with numerous rivers to the east

• Solomon Islands

  mostly rugged mountains with some low coral atolls

• Somalia

  mostly flat to undulating plateau rising to hills in north

• South Africa

  vast interior plateau rimmed by rugged hills and narrow coastal plain

• South Georgia and South Sandwich Islands

  most of the islands are rugged and mountainous rising steeply from the sea; South Georgia is largely barren with steep, glacier-covered mountains; the South Sandwich Islands are of volcanic origin with some active volcanoes

• South Sudan

  plains in the north and center rise to southern highlands along the border with Uganda and Kenya; the White Nile, flowing north out of the uplands of Central Africa, is the major geographic feature of the country; The Sudd (a name derived from floating vegetation that hinders navigation) is a large swampy area of more than 100,000 sq km fed by the waters of the White Nile that dominates the center of the country

• Southern Ocean

  the Southern Ocean is 4,000 to 5,000-m deep over most of its extent with only limited areas of shallow water; the Antarctic continental shelf is generally narrow and unusually deep, its edge lying at depths of 400 to 800 m (the global mean is 133 m); the Antarctic icepack grows from an average minimum of 2.6 million sq km in March to about 18.8 million sq km in September, better than a sixfold increase in area

  major surface currents: the cold, clockwise-flowing Antarctic Circumpolar Current (West Wind Drift; 21,000 km long) moves perpetually eastward around the continent and is the world's largest and strongest ocean current, transporting 130 million cubic meters of water per second - 100 times the flow of all the world's rivers; it is also the only current that flows all the way around the planet and connects the Atlantic, Pacific, and Indian Oceans; the cold Antarctic Coastal Current (East Wind Drift) is the southernmost current in the world, flowing westward and parallel to the Antarctic coastline

• Spain

  large, flat to dissected plateau surrounded by rugged hills; Pyrenees Mountains in north

• Spratly Islands

  small, flat islands, islets, cays, and reefs

• Sri Lanka

  mostly low, flat to rolling plain; mountains in south-central interior

• Sudan

  generally flat, featureless plain; desert dominates the north

• Suriname

  mostly rolling hills; narrow coastal plain with swamps

• Svalbard

  rugged mountains; much of the upland areas are ice covered; west coast clear of ice about half the year; fjords along west and north coasts

• Sweden

  mostly flat or gently rolling lowlands; mountains in west

• Switzerland

  mostly mountains (Alps in south, Jura in northwest) with a central plateau of rolling hills, plains, and large lakes

• Syria

  primarily semiarid and desert plateau; narrow coastal plain; mountains in west

• Taiwan

  eastern two-thirds mostly rugged mountains; flat to gently rolling plains in west

• Tajikistan

  mountainous region dominated by the Trans-Alay Range in the north and the Pamirs in the southeast; western Fergana Valley in north, Kofarnihon and Vakhsh Valleys in southwest

• Tanzania

  plains along coast; central plateau; highlands in north, south

• Thailand

  central plain; Khorat Plateau in the east; mountains elsewhere

• Timor-Leste

  mountainous

• Togo

  gently rolling savanna in north; central hills; southern plateau; low coastal plain with extensive lagoons and marshes

• Tokelau

  low-lying coral atolls enclosing large lagoons

• Tonga

  mostly flat islands with limestone bedrock formed from uplifted coral formation; others have limestone overlying volcanic rock

• Trinidad and Tobago

  mostly plains with some hills and low mountains

• Tunisia

  mountains in north; hot, dry central plain; semiarid south merges into the Sahara

• Turkey

  high central plateau (Anatolia); narrow coastal plain; several mountain ranges

• Turkmenistan

  flat-to-rolling sandy desert with dunes rising to mountains in the south; low mountains along border with Iran; borders Caspian Sea in west

• Turks and Caicos Islands

  low, flat limestone; extensive marshes and mangrove swamps

• Tuvalu

  low-lying and narrow coral atolls

• Uganda

  mostly plateau with rim of mountains

• Ukraine

  mostly fertile plains (steppes) and plateaus, with mountains found only in the west (the Carpathians) or in the extreme south of the Crimean Peninsula

• United Arab Emirates

  flat, barren coastal plain merging into rolling sand dunes of vast desert; mountains in east

• United Kingdom

  mostly rugged hills and low mountains; level to rolling plains in east and southeast

• United States

  vast central plain, mountains in west, hills and low mountains in east; rugged mountains and broad river valleys in Alaska; rugged, volcanic topography in Hawaii

• United States Pacific Island Wildlife Refuges

  low and nearly flat sandy coral islands with narrow fringing reefs that have developed at the top of submerged volcanic mountains, which in most cases rise steeply from the ocean floor

• Uruguay

  mostly rolling plains and low hills; fertile coastal lowland

• Uzbekistan

  mostly flat-to-rolling sandy desert with dunes; broad, flat intensely irrigated river valleys along course of Amu Darya, Syr Darya (Sirdaryo), and Zarafshon; Fergana Valley in east surrounded by mountainous Tajikistan and Kyrgyzstan; shrinking Aral Sea in west

• Vanuatu

  mostly mountainous islands of volcanic origin; narrow coastal plains

• Venezuela

  Andes Mountains and Maracaibo Lowlands in northwest; central plains (llanos); Guiana Highlands in southeast

• Vietnam

  low, flat delta in south and north; central highlands; hilly, mountainous in far north and northwest

• Virgin Islands

  mostly hilly to rugged and mountainous with little flat land

• Wake Island

  atoll of three low coral islands, Peale, Wake, and Wilkes, built up on an underwater volcano; central lagoon is former crater, islands are part of the rim

• Wallis and Futuna

  volcanic origin; low hills

• West Bank

  mostly rugged, dissected upland in west, flat plains descending to Jordan River Valley to the east

• World

  tremendous variation of terrain on each of the continents; check the World 'Elevation' entry for a compilation of terrain extremes; the world's ocean floors are marked by mid-ocean ridges while the ocean surfaces form a dynamic, continuously changing environment; check the 'Terrain' field and its 'major surface currents' and 'ocean zones' subfields under each of the five ocean (Arctic, Atlantic, Indian, Pacific, and Southern) entries for further information on oceanic environs
  
  Ten Cave Superlatives: compiled from "Geography - note(s)" under various country entries where more details may be found
  
  largest cave: Son Doong in Phong Nha-Ke Bang National Park, Vietnam is the world's largest cave (greatest cross sectional area) and is the largest known cave passage in the world by volume; it currently measures a total of 38.5 million cu m (about 1.35 billion cu ft); it connects to Thung cave (but not yet officially); when recognized, it will add an additional 1.6 million cu m in volume
  
  largest ice cave: the Eisriesenwelt (Ice Giants World) inside the Hochkogel mountain near Werfen, Austria is the world's largest and longest ice cave system at 42 km (26 mi)
  
  longest cave: Mammoth Cave, in west-central Kentucky, is the world's longest known cave system with more than 650 km (405 mi) of surveyed passageways
  
  longest salt cave: the Malham Cave in Mount Sodom in Israel is the world's longest salt cave at 10 km (6 mi); its survey is not complete and its length will undoubtedly increase
  
  longest underwater cave: the Sac Actun cave system in Mexico at 348 km (216 mi) is the longest underwater cave in the world and the second longest cave worldwide
  
  longest lava tube cave: Kazumura Cave on the island of Hawaii is the world's longest and deepest lava tube cave; it has been surveyed at 66 km (41 mi) long and 1,102 m (3,614 ft) deep
  
  deepest cave: Veryovkina Cave in the Caucasus country of Georgia is the world's deepest cave, plunging down 2,212 m (7,257 ft)
  
  deepest underwater cave: the Hranice Abyss in Czechia is the world's deepest surveyed underwater cave at 404 m (1,325 ft); its survey is not complete and it could end up being some 800-1,200 m deep
  
  largest cave chamber: the Miao Room in the Gebihe cave system at China's Ziyun Getu He Chuandong National Park encloses some 10.78 million cu m (380.7 million cu ft) of volume
  
  largest bat cave: Bracken Cave outside of San Antonio, Texas is the world's largest bat cave; it is the summer home to the largest colony of bats in the world; an estimated 20 million Mexican free-tailed bats roost in the cave from March to October making it the world's largest known concentration of mammals

• Yemen

  narrow coastal plain backed by flat-topped hills and rugged mountains; dissected upland desert plains in center slope into the desert interior of the Arabian Peninsula

• Zambia

  mostly high plateau with some hills and mountains

• Zimbabwe

  mostly high plateau with higher central plateau (high veld); mountains in east