sonar
hydrophones
World War I submarines were primarily used to locate and attack surface cargo and warships.
They were used by submarines to navigate when not in open waters, They were also used by submarines and anti-submarine ships to locate enemy submarines.
Type your answer here... ASDIC
During World War I, the primary instrument used to detect the sound of submarines was the hydrophone. This underwater listening device allowed ships to detect the noises made by submarines, such as engine sounds and propeller movements. Hydrophones were often deployed in arrays and played a crucial role in anti-submarine warfare, helping to locate and track enemy submarines.
Sonar was used widely in World War II in an effort to locate enemy submarines. It wasn't as sophisticated as it is today, but it did help. Actual numbers are difficult to come by, but sonar was effective in the successful attacks on several submarines.
During WW2, all the major countries involved used submarines.
During WWII, Allied warships used ASDIC (an early, crude form of Sonar), airplanes (some ships carried recoverable seaplanes), and visual lookouts (binoculars) to spot submarines and direct attacking vessels to the contact.
Submarines todaee are used for underwater exploration,funn,new life underwater.
Shallow diving submarines are used for reef watching in many parts of the world.
Nuclear energy is used to power most modern submarines
submarines were used in WW1 and the weapons used were torpedos and a deck gun.
Both the Union and the Confederate had submarines, but the Confederate used them more often.