Torpedo...
An underwater bomb is called a 'depth charge.
depth charge
to use the underwater bomb underwater you need set : iron boots, and some water bombs( the zora armor may help though ).
This is an old and a common term. The torpedo has been used since the first submarine's were used in war time.
The weapon described is a depth charge.
Crossroads Baker was detonated underwater in Bikini Lagoon.
An underwater bubble blower.
A... bomb?
Areas of underwater ground are called seabeds or ocean floors.
It was called the Nucleus Bomb.
Underwater sound detecting systems are called hydrophones. These devices are used to listen to and record sounds underwater, such as those produced by marine animals or underwater activities.
Being completely underwater is referred to as being submerged.