Despite the name, the Black Sea is not actually black - it is blue or green, just like most seas. Nobody is quite sure why it got the name. One theory is that sailors thought its winter storms looked dark and stormy. Another is that very deep down the water is unusually still and dark.
Three different kinds of dolphin live in the Black Sea: bottlenose dolphins, common dolphins and a tiny dolphin called the harbour porpoise. They sometimes follow boats and leap out of the water. Scientists watch them carefully to make sure the Black Sea stays a good home for them.
Odesa is Ukraine's biggest city on the coast. It is famous for its long flight of stone steps - the Potemkin Stairs - that lead from the city down to the harbour. There are 192 steps, and they were designed so that from the top you only see the platforms, and from the bottom you only see the steps. It is like a clever optical illusion built in stone.
Further along the coast are huge wetlands and a small Ukrainian section of the Danube River delta - one of the biggest wetlands in Europe and an important resting place for migrating birds. Millions of birds stop there on their way south for the winter.