"Coastal defence and fortification"@en . . . "Although most coastal fortifications are on the coast, not all are. Instead, some are off the coast on islands, artificial islands, or are specially built structures. All the sea forts share the characteristic that at least at high tide they are completely surrounded by water. Some, such as Fort Denison or Fort Sumter, are actually in harbours, but most are off the coast. Again, some, such as for example Br\u00E9hon Tower, completely occupy small islands, although others, such as for example Flakfortet and Pampus, are on artificial islands built up on shoals. Fort Louvois is on a built-up island, 400 meters from the shore, and connected to it by a causeway that high tide completely submerses. The most elaborate sea fort is Murud-Janjira, which is so extensive that one might truly call it a sea "@en . . . . "Although most coastal fortifications are on the coast, not all are. Instead, some are off the coast on islands, artificial islands, or are specially built structures. All the sea forts share the characteristic that at least at high tide they are completely surrounded by water. Some, such as Fort Denison or Fort Sumter, are actually in harbours, but most are off the coast. Again, some, such as for example Br\u00E9hon Tower, completely occupy small islands, although others, such as for example Flakfortet and Pampus, are on artificial islands built up on shoals. Fort Louvois is on a built-up island, 400 meters from the shore, and connected to it by a causeway that high tide completely submerses. The most elaborate sea fort is Murud-Janjira, which is so extensive that one might truly call it a sea fortress. The most recent sea forts were the Maunsell Forts, which the British built during World War II. One type consisted of a concrete pontoon barge on which stood two cylindrical towers on top of which was the gun platform mounting. They were laid down in dry dock and assembled as complete units. They were then fitted out before being towed out and sunk onto their sand bank positions in 1942. The other type consisted of seven interconnected steel platforms built on stilts. Five platforms carried guns arranged in a semicircle around the sixth platform, which contained the control centre and accommodation. The seventh platform, set further out than the gun towers, was the searchlight tower."@en . . . . . .