Anti-submarine warfare

thumb|upright=1.35|French Georges Leygues-class frigate|F70 type frigates (here, ) are fitted with [[variable depth sonar (VDS) type DUBV43 or DUBV43C towed sonars.]] thumb|upright=1.35|A sonar image of the Soviet Navy minesweeper T-297, formerly the Latvian Virsaitis, which was shipwrecked in December 1941 in the [[Gulf of Finland.]]

explosive weapon for use in seas and waterways, triggered by the target's approach

thumb|Graph showing a tropical ocean thermocline (depth vs. temperature). Note the rapid change between 100 and 1000 meters. The temperature is nearly constant after 1500 meters depth.

anti-submarine weapon

branch of naval warfare

thumb|upright=1.35|First SOSUS stations Sound Surveillance System (SOSUS) was the original name for a submarine detection system based on passive sonar developed by the United States Navy to track Soviet submarines. The system's true nature was classified with the name and acronym SOSUS classified as well. The unclassified name Project Caesar was used to cover the installation of the system and a cover story developed regarding the shore stations, identified only as a Naval Facility (NAVFAC), being for oceanographic research. The name changed to Integrated Undersea Surveillance System (IUSS) i

thumb|right|300px|Sonobuoy being loaded onto a USN P-3C Orion aircraft thumb|Hand deployment of a sonobuoy in the Arctic Ocean from the aft deck of the R/V Sikuliaq

missile designed to target submerged vessels

instrument for detecting variations in the Earth's magnetic field

form of defence against naval torpedoes

horizontal layer of water in the ocean at which depth the speed of sound is at its minimum

Royal Navy captain (1896–1944)

thumb|A bathythermograph The bathythermograph, or BT, also known as the Mechanical Bathythermograph, or MBT; is a device that holds a temperature sensor and a transducer to detect changes in water temperature versus depth down to a depth of approximately 285 meters (935 feet). Lowered by a small winch on the ship into the water, the BT records pressure and temperature changes on a coated glass slide as it is dropped nearly freely through the water. While the instrument is being dropped, the wire is payed out until it reaches a predetermined depth, then a brake is applied and the BT is drawn ba

Military towed torpedo decoy system

passive ship defensive device

the passages between the Norwegian Sea and central Atlantic left undefended early in WWII

US Navy information processing system

barrier placed across the mouth of a harbour or a strait for protection against submarines

command and control technology used in ships and aircraft carriers

device mounted on the bows of some naval submarines to cut through anti-submarine netting

overview of naval operations during the Indo-Pakistani War of 1971