Other forms: sonars
Sonar is a method of finding objects under water using sound waves. If the Titanic had been able to use sonar, it never would have hit that iceberg.
There are two kinds of sonar: active sonar, which sends sounds out and listens for their echoes, and passive sonar, which records existing sounds. Both allow boat and submarine pilots, explorers, the military, and scientists to determine how far away underwater objects are and approximately how large they are. Leonardo da Vinci gets the credit for inventing sonar when he inserted a tube in the water and listened for the sound of distant ships in 1490.