Submarines have sonars.
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.
By an electronic device called 'sonar' .
The development of radar helped detect underwater submarines.
Sonar. Active and passive
they use sonar like bats do to detect objects that are in their path
Modern naval ships use some form of Sonar to detect submarines. Additionally, some ships are equipped with Magnetic Anomaly Detectors (MAD gear) that detect a submarine's impact on the Earth's magnetic field in that area. The gear is typically carried aboard helicopters temporarily stationed on the ship.
sound wavers are affected by propellers
They are mapped by sonar. The same technology they use to detect submarines from battleships / carriers.
Type your answer here... ASDIC
Sonar was used to detect and hunt submarines in WW2
Submarines use echolocation to detect, locate, and avoid obstacles underwater, as well as to navigate their surroundings. By emitting sound waves and analyzing the echoes that bounce off objects, submarines can map their environment in conditions where visual navigation is limited or impossible.