The world’s largest Indoor Aquarium is Dubai Aquarium. It has an enormous tank with the capacity to hold 10 million litres of water. The aquarium has more than 33,000 aquatic animals from over 200 species, such as sharks and rays. On the second level is the largest Underwater Zoo where different kinds of marine animals, including giant spider, crabs, sea-horses, water-rats, jelly-fish, penguins and crocodiles are found.