An anti-submarine net or anti-submarine boom is a boom placed across the mouth of a harbour or a strait for protection against submarines. Net laying ships would be used to place and remove the nets. The US Navy used anti-submarine net in the Pacific War to protect major US Naval Advance Bases. Some Net cutter submarines were used in the war. Examples of anti-submarine nets Lake Macquarie anti-submarine boom Indicator net Naval operations in the Dardanelles Campaign Sydney Harbour anti-submarine boom net Isle of Bute during World War II - Anti-submarine net in the Clyde Estuary in Scotland (Item 4) See also Anti-submarine warfare Jumping wire (of a submarine) Net cutter (submarine) Net laying ship Torpedo net References Anti-submarine warfare Anti-submarine weapons Auxiliary gateship classes