Aside from what we can see from the outside, there are a dozen or so marines sealed INSIDE?
What’s the normal egress?
IIRC, there's a single hatch built inside the big hatch that's about the size of a doorway; this allows people in and out of the troop compartment individually.
I don't know what it would take to drop the big hatch on a sinking craft (besides incredible calmness and presence of mind), but it's a safe bet that if half the people on board are dead, it was never opened.
Normal egress is a ramp that drops in the back.
This is an amphibious assault vehicle. It delivers Marines to the shore and can also be used to ferry supplies from ship to shore.
This vid shows the vehicles launching from the well deck of a ship. at the end of the clip shows the tracs going onto the beach and Marines coming out of them to conduct an assault training exercise.
There are also hatches that run down both sides of the top of the vehicle that can be used for various purposes, including emergency exist. Those can be seen in the next vid once the tracs reach the beach and start maneuvering inland.
Beach Landing in Amphibious Assault Vehicles
Sad fact is, not all Marines can swim well, as weird as that sounds. And when loaded up for an assault, Marines are wearing 60 or more pounds of gear, including the armored vest and such that can not be quickly removed.
It’s dangerous work. Always has been. And there but for the grace of God, I’d have gone if a similar accident had occurred when I was riding in those beasts for training purposes.
It’s one of the many things we knew could happen and hoped didn’t happen.
In this vid, at about the 4:30 mark, you can see Marines exiting the amtracs.