Something I read a while ago got my attention again recently... There is a large cave near the left side of the area where you have to open the vault, on the ground level, almost below the vault door. There was a thread one day about a chest that spawned in this cave after building the spire or something, can't quite remember what had to be done. Anyway on the right side of this area, near campus-9 entrance and the cliffs, there is another similar cave, that is deeper than most others. In campus-9 itself, under the large circular building on your left where you would summon your ghost in a previous mission, there is a cave like the others I'm mentioning, much deeper than any other. I don't know if outside of the vault even matters anymore but if you keep trekking along all the way to the gate lord area, ( where people speculate this area/gate could be linked to cracking the secret of the vault) at the very far edge of this area, near the cliffs, there is yet another large deep cave. Now I don't think I've seen any of these larger caves anywhere else on Venus but at the vault and campus-9. The only reason I bring this up because I've never seen enemies spawn out of them, and the location of the last one in particular makes no sense to me as why it would be there. Maybe it's linked... Maybe not, maybe I need a smart person to tell me...