Submarines were sometimes referred to as submersibles.
During World War 2, it is reported that over 2,000 variants of Japanese Submarines were used during World War 2. Out of this, it is estimated that 10,000s were likely to be used during WW2.
The British lost 76 submarines during WWII.
The submarines were either called "submarines" or "U-boats." The German submarine was called the "U-boat"
Germany called there submarines U boats
the U boats..
In World War 2 submarines people had many jobs. Some listened to different radio signals, and others watched the sonar. There were also navigators, torpedo loaders and shooters, and preachers. In most submarines there were surgeons.
An estimation of about 600 subs were operated during the war.
ASDIC
More than you can afford
Britain, France, Germany, Italy and USA all used submarines during WW1
Why don't you just Google "World War 1 Submarines?"