Neutral buoyancy is not stable. Any kind of water movement will move it up or down as will momentum. Submarines use something called dive planes which are akin to various control surfaces on an aircraft. They point the nose in the desired direction (up/down) to keep a stable depth. As far as I know, there is no word in the English language for this action.
Only two things are infinite, the universe and human stupidity, and I'm not sure about the former.
Albert Einstein
Albert Einstein