Inside St John’s Fortress is the Aquarium and Maritime Museum. The Aquarium holds a large selection of fish and other maritime dwellers in the twenty-seven tanks. There are also displays of sea horses and anemones. The Maritime Museum holds displays relating to the Ragusan sea industry such as sea charts and models of the Dubrovnik boats through history. The Maritime Museum is divided into four collections: the Dubrovnik Republic, steam, the Second World War and navigation.