To the ancients, "seven" often meant "many," and before the fifteenth
century, the many seas of the world were:
* the Red Sea
* the Mediterranean Sea
* the Persian Gulf
* the Black Sea
* the Adriatic Sea
* the Caspian Sea
* the Indian Ocean
see: http://www.whoi.edu/info/seven-seas.html
All the best
Riccardo Giannuzzi-Savelli