Pry open the metal door in the corner, near the doorway to the room with the Oriental rug and sleeping mats where you dropped in.
Stand in the doorway overlooking the partially flooded hallway. Look up to the left to spot another totem (2/5) for the Sun Killer Challenge.
The next totem (3/5) is directly across the hall beyond the rectangular window. It's difficult to spot, but it's hanging on the left side of the window, beyond the opening in the rubble, just in front of one of those creepy dangling bodies.
When you've destroyed both totems, jump from the doorway to grab the edge of the rectangular window opening.
Drop down on the other side.
Most of this room is inaccessible, due to the huge pile of rubble, but in the small space below the window there's a food cache and a GPS cache (2/3). Take what you need and then scramble back up the wall and drop down in the flooded hallway.