Good grief man, pull yourself together! We don't need defeatest talk like that.
BD in a very early post was 50% correct or even 75% correct. So eliminate the wrong 25% & substitute the correct thing from the more recent posts & you are there.
The answer is not something obscure, it will seem obvious when you know the answer. But nobody has brought together all the correct pieces of evidence together to get it.
Nope he's not doing any work to a vehicle, bridge, BARV or submarine. He's not lifting anything up with ropes or air bags, blowing it up with explosives, repairing it, dragging or pushing it.
Nope, although landing craft are part of it they are more of a secondary role to the answer.
So we should now have got submarines, BARVs & to some degree landing craft out of the way..........
There is no tank on the left. You are correct the tank he is in does fill up with water, hence the scuba gear. But you haven't quite got to the reason for it filling.
Nope Neil, Bodge Deep was nearly there but as I said, his answer was only 50% correct! But people focussed on the wrong 50%! Or it could be argued that he was actually 75% correct!
Rather than humiliate this poor man any more by tilting his kiosk, the diagonal I think is to suggest the position that the water would be if the chamber was so tilted. I think!