Was the Baltic of the distant past the same sea that we know today? What do fish eat in the Baltic Sea? How can we estimate the size of fish stocks and their location in the Baltic Sea? This, and other issues, is what interests the scientists at the Sea Fisheries Institute in Gdynia. SFI present the wealth of the seas and oceans and offer educational courses at the Gdynia Aquarium. The youngest visitors learn all the secrets of life on the beaches and in the coral reefs. Who knows, maybe one of them will become a scientist and solve the next sea mystery?