It depends on the depth. But if the leak is noticed at say 20m they would have surfaced. A leak with the amount of pressure at 1000m would cause a high speed

It depends on the depth. But if the leak is noticed at say 20m they would have surfaced. A leak with the amount of pressure at 1000m would cause a high speed jet like from a water cutter. That in turn would cause the material around the leak to be ground away. This is really bad for the structural integrity and boom the whole thing implodes in a fraction of a second.