"Its as simple as that. The set has an open back, with no wall or door. If real, the ocean would just rush in. Its cool that the mini sub fits and clips inside, but the gaping void of a back destroys all illusion. The middle passenger compartment als9 needs studs on the floor for minifig. Lego could have done so much better.
I am going to edit the build to have the mini-sub attach to the roof, and build a bottom hinged backdoor."