When was sonar first used on submarines and who used it?

The earliest use of Submarine Sonar was by the British Royal Navy. In 1915, 10 British H class submarines were equipped with the first passive sonar system, known as a Fessenden Oscillator. The FO was able to detect a target, but could not establish a bearing, which is critical to target tracking. Further research into Hydrophone and Transducer technology eventually led to active and passive sonar systems, though those old systems were extremely basic by today's modern sonar standards.

However, little has changed except for the bells and whistles on modern systems. Submarine Sonar, like then, still use Transducers and Hydrophones for operation. The only thing that has changed is how the information is processed and displayed to the operator.

The Oceans haven't changed much either.