"This is actually how we would get SEALs off the ship submerged," Eichenlaub said. "So you would stick a platoon of SEALs in here — 14 guys ... You fill this chamber with water until you match the outer sea pressure. Once the pressure in and outside the ship match, the hatch will lift off open and they can swim out of a fully filled chamber into open ocean."
Once the SEALs are in open water, they can retrieve any weapons or gear from the SOF box (which we saw being loaded into the tower in the first picture).