Basically, the Marines burned through the outer hull, moved into the inner
hull (like any good vessel, this one is double hulled), then came up at a
right angle, looking for a good wall to come through. You *don't* want to
come up through the floor, because then you have to climb out one or two at a
time, which makes you a sitting duck. Better to move off a few feet, and
come up via a section between walls and blow your way through so you can come
out en masse.