After you are able to find the way to get our from the water, you fall down from the roof and get into a place where there's a lot of tanks and pipes, but there is no way around to get to the stairs on the other side. What is the trick here ??
pretty sure I know where your talking about. took me awhile to figure it out too, go in the room away from the pit that has the water at the bottom and large pipe, once your in there you should be able to go around to the right and look for a wheel valve. turn that and it will lower the water level (or raise it, i cant remember) then go looking what was uncovered.
use the grav gun to lift the bar off the door. There are two doors like this, one is a caged door and u can lift the bar directly off the door, the second is steel double doors....you will have to go into another room and lift the bar with the grav gun through a window.
Hope that helps, I'm pretty sure you are stuck at one of these doors