Seas, gulfs and bays at true size, beside the countries they match
Natural Earth draws 282 marine areas, but for labels, not as a survey: it cuts seas at named sub-areas and splits the oceans at the equator. Each one listed has been measured and checked against its published area, and 42 passed, some of them counted from their named parts. Below they are drawn at true scale and matched to the country nearest each in size.
This page is about size, not about borders or names. A lake or a sea has no legal boundary of its own, so the outlines are cartographic ones, and every area is shown beside the published figure it was checked against.
The largest, at one scale
Every outline is drawn at the same scale; select one to open its page.
At a glance
- The Arabian Sea, the largest of the 42 seas on sizeversus, is 1.30× the size of the South China Sea, the next, and 457× the size of the Frobisher Bay, the smallest.
- The ten largest cover 20,258,000 km² together, 1.19× the size of Russia.
- 34 of the 42 are larger than Belgium (30,700 km²).
- 31 of the 42 are larger than Ireland (69,400 km²).
- 30 of the 42 are larger than Austria (84,000 km²).
- The Arabian Sea alone is larger than 206 of the 212 countries on sizeversus, and than 51 of the 51 US states and districts.
- the Mediterranean Sea, counted with its named marginal seas, covers 2,521,000 km², 91% of the size of Argentina.
- the Gulf of Mexico, counted with its named marginal seas, covers 1,562,000 km², about the same size as Mongolia.
- the Baltic Sea, counted with its named marginal seas, covers 381,000 km², about the same size as Norway.
- 15 of the 42 are flagged because their outline is more than 5% from the published area; the rest are within 5%.
Seas counted with their parts
Natural Earth’s marine polygons cut some seas into named sub-areas. Where the pieces of a sea are known and their sum agrees with the published area of the whole, they are counted together: Mediterranean Sea, Gulf of Mexico, Baltic Sea. Each is listed with its pieces on its own page.
Every sea matched to a country
Largest first. The match is the country closest in area from Natural Earth’s country list (contested places and dependencies are never used), and the second is the closest US state or Chinese province, or else the closest sea, when one is within a factor of 3. A flag means the outline is more than 5% from the published area.
- Arabian Sea4,129,000 km² · flaggedSize ofIndia1.31× · 3,151,000 km²US stateAlaska2.74× · 1,505,000 km²
- South China Sea3,169,000 km² · flaggedSize ofIndia1.01× · 3,151,000 km²US stateAlaska2.11× · 1,505,000 km²
- Caribbean Sea2,829,000 km²Size ofArgentina1.02× · 2,783,000 km²US stateAlaska1.88× · 1,505,000 km²
- Bering Sea2,232,000 km²Size ofAlgeria0.97× · 2,309,000 km²US stateAlaska1.48× · 1,505,000 km²
- Bay of Bengal2,037,000 km² · flaggedSize ofMexico1.04× · 1,958,000 km²US stateAlaska1.35× · 1,505,000 km²
- Sea of Okhotsk1,459,000 km² · flaggedSize ofMongolia0.93× · 1,565,000 km²US stateAlaska0.97× · 1,505,000 km²
- Barents Sea1,378,000 km²Size ofPeru1.07× · 1,290,000 km²US stateAlaska0.92× · 1,505,000 km²
- Greenland Sea1,183,000 km²Size ofSouth Africa0.97× · 1,220,000 km²ProvinceInner Mongolia1.03× · 1,144,000 km²
- Sea of Japan959,000 km²Size ofEgypt0.96× · 1,001,000 km²ProvinceInner Mongolia84% · 1,144,000 km²
- Labrador Sea884,000 km² · flaggedSize ofPakistan1.01× · 873,000 km²ProvinceQinghai1.24× · 714,000 km²
- Kara Sea815,000 km² · flaggedSize ofNamibia0.99× · 823,000 km²ProvinceQinghai1.14× · 714,000 km²
- Solomon Sea745,000 km²Size ofChile1.01× · 736,000 km²ProvinceQinghai1.04× · 714,000 km²
- Red Sea446,000 km²Size ofSweden1.00× · 446,000 km²ProvinceHeilongjiang0.99× · 452,000 km²
- Black Sea422,000 km²Size ofIraq0.97× · 437,000 km²US stateCalifornia1.03× · 410,000 km²
- Caspian Sea379,000 km²Size ofNorway0.99× · 382,000 km²US stateMontana1.00× · 379,000 km²
- Yellow Sea377,000 km²Size ofJapan1.01× · 374,000 km²US stateMontana0.99× · 379,000 km²
- Great Barrier Reef348,000 km²Size ofGermany0.97× · 358,000 km²US stateMontana0.92× · 379,000 km²
- Bismarck Sea331,000 km² · flaggedSize ofFinland0.99× · 333,000 km²US stateNew Mexico1.05× · 315,000 km²
- Sulu Sea326,000 km² · flaggedSize ofVietnam0.99× · 329,000 km²US stateNew Mexico1.04× · 315,000 km²
- Gulf of Thailand299,000 km² · flaggedSize ofItaly0.99× · 301,000 km²US stateArizona1.01× · 295,000 km²
- Gulf of Carpentaria290,000 km²Size ofPhilippines0.99× · 293,000 km²US stateNevada1.01× · 287,000 km²
- Persian Gulf243,000 km²Size ofUnited Kingdom1.00× · 244,000 km²ProvinceGuangxi1.03× · 237,000 km²
- Gulf of Saint Lawrence242,000 km² · flaggedSize ofUnited Kingdom0.99× · 244,000 km²ProvinceGuangxi1.02× · 237,000 km²
- Molucca Sea217,000 km² · flaggedSize ofGuyana1.03× · 211,000 km²US stateIdaho1.00× · 216,000 km²
- Bay of Biscay216,000 km²Size ofGuyana1.02× · 211,000 km²US stateIdaho1.00× · 216,000 km²
- Gulf of California172,000 km² · flaggedSize ofUruguay0.97× · 177,000 km²US stateWashington State0.99× · 174,000 km²
- Adriatic Sea141,000 km²Size ofTajikistan0.99× · 142,000 km²ProvinceAnhui1.01× · 140,000 km²
- Gulf of Bothnia120,000 km²Size ofMalawi1.01× · 119,000 km²ProvinceFujian1.00× · 121,000 km²
- Savu Sea102,000 km²Size ofIceland1.00× · 102,000 km²ProvinceZhejiang1.01× · 101,000 km²
- White Sea92,200 km²Size ofPortugal1.01× · 91,400 km²US stateIndiana0.98× · 94,300 km²
- Bohai Sea77,900 km²Size ofSerbia1.00× · 77,600 km²US stateSouth Carolina0.97× · 80,200 km²
- Ungava Bay49,600 km²Size ofSlovakia1.02× · 48,500 km²ProvinceNingxia0.95× · 52,100 km²
- Bali Sea43,400 km²Size ofDenmark1.02× · 42,700 km²ProvinceNingxia83% · 52,100 km²
- Sea of Azov37,600 km²Size ofNetherlands1.01× · 37,100 km²ProvinceHainan1.11× · 33,800 km²
- Gulf of Finland30,400 km²Size ofBelgium0.99× · 30,700 km²ProvinceHainan90% · 33,800 km²
- Kattegat24,000 km² · flaggedSize ofRwanda0.95× · 25,300 km²US stateNew Hampshire0.99× · 24,300 km²
- Gulf of Riga18,200 km²Size ofFiji0.96× · 18,900 km²US stateHawaii1.08× · 16,800 km²
- Garabogazköl17,000 km² · flaggedSize ofEswatini0.99× · 17,100 km²US stateHawaii1.01× · 16,800 km²
- Bay of Fundy15,600 km²Size ofEast Timor1.03× · 15,100 km²ProvinceBeijing0.96× · 16,300 km²
- Chesapeake Bay11,700 km²Size ofQatar1.05× · 11,200 km²ProvinceTianjin1.02× · 11,500 km²
- Sea of Marmara11,600 km²Size ofQatar1.04× · 11,200 km²ProvinceTianjin1.01× · 11,500 km²
- Frobisher Bay9,030 km² · flaggedSize ofLebanon0.90× · 10,000 km²ProvinceTianjin79% · 11,500 km²
The closest matches in size
The oceans are not drawn
Natural Earth splits the Pacific and the Atlantic at the equator and leaves out their marginal seas, so no ocean outline agrees with its published area, and none is drawn or matched on sizeversus. Their published areas are shown for scale.
| Ocean | Published, km² | Natural Earth outline, km² | Difference |
|---|---|---|---|
| Pacific Ocean | 161,760,000 | 139,016,000 | -14.1% |
| Atlantic Ocean | 106,460,000 | 71,581,000 | -32.8% |
| Indian Ocean | 70,560,000 | 60,420,000 | -14.4% |
| Southern Ocean | 20,327,000 | 16,741,000 | -17.6% |
| Arctic Ocean | 14,056,000 | 5,200,000 | -63% |
Left out, and why
210 outlines were measured and not kept: either the outline differs from the published area by more than 10%, or Wikidata has no published area to check it against. The largest, with the reason:
| Name | Outline, km² | Published, km² | Difference | Reason |
|---|---|---|---|---|
| Philippine Sea | 5,555,000 | 5,000,000 | +11.1% | outline differs |
| Coral Sea | 3,970,000 | 4,791,000 | -17.1% | outline differs |
| Tasman Sea | 3,349,000 | 2,300,000 | +45.6% | outline differs |
| Sargasso Sea | 3,009,000 | 5,180,000 | -41.9% | outline differs |
| Ross Sea | 1,661,000 | 637,000 | +160.8% | outline differs |
| Norwegian Sea | 1,548,000 | 1,383,000 | +11.9% | outline differs |
| Mozambique Channel | 1,373,000 | – | – | no published area |
| Weddell Sea | 1,335,000 | 2,800,000 | -52.3% | outline differs |
| Great Australian Bight | 1,236,000 | – | – | no published area |
| Laccadive Sea | 815,000 | – | – | no published area |
| Hudson Bay | 771,000 | 1,243,000 | -38% | outline differs |
| Banda Sea | 732,000 | 470,000 | +55.7% | outline differs |
| East China Sea | 728,000 | 1,249,000 | -41.7% | outline differs |
| Arafura Sea | 727,000 | 650,000 | +11.9% | outline differs |
Names
Governments and organisations use different names for this body of water, or for parts of it. Size Versus uses the name that Natural Earth’s file gives as the title, lists the other names it can source, and takes no position on which is right. The wording is the same in every language. The title of a page is Natural Earth’s name; the other names each page lists are ones that Natural Earth or Wikidata records, with that source named.
Sources and method
- Outlines
- Natural Earth, 1:10m Marine Areas (geography_marine_polys), public domain. Lakes and reservoirs, marine areas and island outlines are three Natural Earth files; countries for the matches come from Natural Earth's Admin 0 file.
- What was checked
- Every outline was measured on the WGS84 ellipsoid and compared with the area Wikidata (CC0) publishes for it, fetched 2026-11-11. Within 2% it agrees, within 5% it is near, within 10% it is kept and flagged; beyond that, or with no published area, it is left out.
- Pieces
- Where Natural Earth draws a sea or a lake system in several outlines, the pieces are named in
config/waters.jsonand counted together only if their sum agrees with the published area of the whole. An outline that lies mostly inside a larger lake (Georgian Bay in Lake Huron) is counted once, in the larger one. - Boundary
- A lake or a sea has no legal boundary. The outlines are cartographic, and the pages say so.
- Data built
- 2026-11-11