Atlantic Ocean

Adriatic Sea
Aegean Sea
Alboran Sea
Argentine Sea
Bay of Biscay
Bay of Bothnia
Bay of Campeche
Bay of Fundy
Baltic Sea
Black Sea
Bothnian Sea
Caribbean Sea
Celtic Sea
Central Baltic Sea
Chesapeake Bay
Davis Strait
Denmark Strait
English Channel
Gulf of Bothnia
Gulf of Guinea
Gulf of Finland
Gulf of Mexico
Gulf of Sidra
Gulf of St. Lawrence
Gulf of Venezuela
Ionian Sea
Labrador Sea
Ligurian Sea
Irish Sea
Marmara Sea
Mediterranean Sea
Mirtoon Sea
North Sea
Norwegian Sea
Sea of Azov
Sea of Crete
Sea of the Hebrides
Sargasso Sea
Thracian Sea
Tyrrhenian Sea
Wadden Sea

Arctic Ocean

Amundsen Gulf
Baffin Bay
Barents Sea
Beaufort Sea
Bering Sea
Chukchi Sea
East Siberian Sea
Greenland Sea
Hudson Bay
James Bay
Kara Sea
Kara Strait
Laptev Sea
Lincoln Sea
Prince Gustav Adolf Sea
Pechora Sea
White Sea

Antarctic Ocean

Amundsen Sea
Bass Strait
Bellingshausen Sea
Davis Sea
Great Australian Bight
Gulf Saint Vincent
Mawson Sea
Ross Sea
Scotia Sea
Spencer Gulf
Weddell Sea

Indian Ocean

Andaman Sea
Arabian Sea
Bay of Bengal
Gulf of Aden
Gulf of Oman
Mozambique Channel
Persian Gulf
Red Sea
Timor Sea

Pacific Ocean

Arafura Sea
Banda Sea
Bering Sea
Bismarck Sea
Bohai Sea
Bohol Sea (also known as the Mindanao Sea)
Camotes Sea
Celebes Sea
Ceram Sea
Chilean Sea
Coral Sea
East China Sea
Flores Sea
Gulf of Alaska
Gulf of California (also known as the Sea of Cortés)
Gulf of Carpentaria
Gulf of Thailand
Halmahera Sea
Java Sea
Koro Sea
Molucca Sea
Philippine Sea
Savu Sea
Sea of Japan
Sea of Okhotsk
Seto Inland Sea
Sibuyan Sea
Solomon Sea
South China Sea
Sulu Sea
Tasman Sea
Visayan Sea
Yellow Sea

Landlocked seas

Aral Sea
Caspian Sea
Chott Melrhir
Dead Sea
Great Lakes of North America (sometimes referred to as inland seas)
Great Salt Lake
Issyk Kul
Lake Balkhash
Lake Chad
Lake Chilwa
Lake Turkana
Lake Van
Namtso
Pyramid Lake
Qinghai Lake
Salton Sea
Tonle Sap