I seem to be having trouble getting into the collosium.....I go in through the door way, go down the hall and throw the switch....then I go down the hall some more and i come to a door that won't open, I can't find any way of opening this door, I have also searched around the big building underwater and the other underground chamber with no avail...

Look for another entrance!

You're at the back door - you can only exit there, not enter! ;)

Wyv

ok, it must be there somewhere, I am getting waterlogged!!! I will find it if it is there.....