This kind of event be pretty nasty - 4 fishermen were killed by a Royal Navy submarine in 1990:
> In a demonstration for some VIP civilian visitors, Greeneville performed an emergency ballast blow surfacing maneuver. As the submarine shot to the surface, she struck Ehime Maru. Within ten minutes of the collision, Ehime Maru sank. Nine of the thirty-five people aboard were killed: four high school students, two teachers, and three crew members.
I seem to remember this happening quite often (yearly, maybe?) during the Cold War in the North Sea and around Norway.