How many oceans and seas are there in the world?

5 oceans and 76 seas.

Here are the details.

1. Pacific Ocean (21 seas):

Bering Sea

Gulf of Alaska

Gulf of California (Sea of Cortez)

Sea of Okhotsk

East Sea (Sea of Japan)

Seto Inland Sea

East China Sea

South China Sea - Beibu Gulf

Sulu Sea

Celebes Sea

Mindanao Sea

Philippine Sea

Flores Sea

Banda Sea

Arafura Sea

Tasman Sea

Yellow Sea - Bohai Sea

Coral Sea

Gulf of Carpentaria

2. Atlantic Ocean (27 seas)

    Hudson Bay - James Bay

    Baffin Bay

    Gulf of St. Lawrence

    Caribbean Sea

    Chesapeake Bay

    Delaware Bay

    Gulf of Mexico

    Sargasso Sea

    North Sea - Baltic Sea - Gulf of Bothnia

    Irish Sea

    Celtic Sea

    English Channel

    Mediterranean Sea

        Adriatic Sea

        Aegean Sea

        Black Sea - Sea of Azov

        Ionian Sea

        Ligurian Sea

        Mirtoon Sea

        Tyrrhenian Sea

        Gulf of Sidra

        Sea of Marmara

        Sea of Crete

3. Indian Ocean (9 seas)

    Red Sea

    Gulf of Aden

    Persian Gulf

    Gulf of Oman

    Arabian Sea

    Bay of Bengal

    Gulf of Thailand

    Java Sea

    Timor Sea

4. Arctic Ocean (8 seas)

Barents Sea

Kara Sea

Beaufort Sea - Amundsen Gulf

Greenland Sea

Chukchi Sea

Laptev Sea

East Siberian Sea

5. Southern Ocean (6 seas)

Amundsen Sea

Weddell Sea

Ross Sea

Great Australian Bight

Gulf St. Vincent

Spencer Gulf

6. Land Bounded Seas (5 seas)

Aral Sea

Caspian Sea

Dead Sea

Sea of Galilee

Salton Sea

(Wikipedia.org)