Unfortunately, there is no definitive answer to this question and the list varies according to some specialists. In older times, "seven" often meant "many" - The many Seas of the World were most commonly
the Mediterranean Sea
the Adriatic Sea
the Persian Gulf
the Black Sea
the Red Sea
the Caspian Sea
the Indian Ocean
Today, we recognize more than 50 Seas or gulfs and the World Ocean is divided into four main Oceans