Somewhat unrelated, so you might want to scroll past:
There is a mercury spill thread here, and the scope of the spill is not clear. Might be huge, might be small, and they debate what one would need huge amounts of mercury for, did they want to kill everyone in Huston, was it for antigravity devices in flying saucers, was it for extracting gold from ore, or what?
But that made me think of U-864 submarine off the coast of Bergen with corroding steel containers with 61 tons of mercury. It was sunk while on the way to Japan, Germany´s allies, with Messerschmidt parts, engineers and mercury (to make bombs)
This is the only story of a submerged submarine that was successfully torpedoed by another submerged submarine.
The British HMS Venturer fired four torpedos 17 seconds apart to positions where it suspected the U-864 might flee. The torpedoes took four minutes to reach the area. U-864 dove down and right into the fourth torpedo.
I noted the 17
[link to en.wikipedia.org (secure)
[link to www.wrecksite.eu (secure)