[Tijeras_Slim]

capable of diving in excess of several thousand meters.
Unpossible!

Not at all, but it's that coming back up thing that might be the problem.

[CrazyIvan]

“Not at all, but it’s that coming back up thing that might be the problem.”

Beat me to it. My first thought was the scene in U 571 where the spook asks how deep the sub will go. “She’ll go all the way to the bottom if we don’t stop her.”