You're not looking online in the right manner.<br />
Although you should NEVER cite wikipedia for an essay, it's good for basic questions. Where things are on a map is pretty basic. Hit up the USSR page and you'll see a map that shows all the soviet republics. Cross-reference that with google maps, and you'll see where the Black and Caspian seas are.<br />
There are three countries (former soviet republics) between the two seas.
One could look at a pre-break-up map.
Can you find the seas on a map? The Black Sea is north of Turkey and the Caspian Sea is north of Iran.