HELP!! I'm stuck in the room with all the girders. I can't seem to get down to the lower level girders. Every time I try hanging and jumping, I just fall in the water. Can anybody help? Much appreciated!

I had same problem! I finally first got the key on upper part. Then I fell in water and the current takes you back, climb back up and start from where you first come in room with girders.Do a quick save.I kept alligning Indy up to differant positions to the right till I finally jump and hit a lower grider. Just look when you fall how close you are and try to move him to hit it. It is easier to to a quick save than go all the way back if you do not make it. You will have to use god mode cheat though because he hits to hard going down. Press F10 Then type TAKLIT_MARION ON

thats great but where do you get the key?

It is the upper right corner all the way in the back.I do not remember for sure how I got there,it was either turn around and drop down and go to left or jumped to a block to right.Also some blocks fell so jump fast.I think you will be able to tell the ones that do.