dafeeeeeeeeeesh
The H.E. punches a few numbers, and the elevator moves up to a new level, after the airlock, a very large room, perhaps kilomaters is size, is revealed, with an equally enormous pneumatic door, a submarine is being built, seems that it is completed, all that was left was to be launched.
H.E.:"Pretty big eh? Took a while to excavate, now hold up a second.
The H.E. then climbs into a large pneumatic suit that is slotted into the wall, and initiates the flooding sequence, soon enough, the large door is open, and the submarine is automatically launched into the depths of the trench they are in.
