In four particular museums and a sea aquarium under one roof, visit a stalactite cave and a megalith, be surprised by the variety of shapes and colours of shells, crystals, minerals, stones and ancient fossils: discover the world below sea level in the sea aquarium. Inside the three-metre thick walled bunker dating from the Second World War are aquariums with fish, crustaceans and molluscs from the North Sea and Wadden Sea. There are also magnificent models of ships, ancient ship and navigation items, and paintings, books and photographs which portray the rich maritime history of the Delfzijl seaport town.