The biggest oceanarium on the Black Sea coast, the Sochi Discovery World Aquarium opened in 2009. It boasts 30 aquariums that together hold five million litres of water, a 40-metre see-through underwater tunnel and tropical rainforest with a waterfall. Among the oceanarium’s many striking inhabitants are sharks, moray eels, jellyfish, corals, rays and turtles. Visitors love to study them for hours before catching one of the shows with all but real mermaids, or watching the fish being fed. Some of the fish can be fed by the visitors themselves, for instance, the greedy Koi Carp. Getting into fights over every little piece of food, these always put on a good show for children and adults alike with their antics. Those who desire can even go diving in the largest aquarium after taking a special lesson and receiving a diving certificate.