I have the helm and breathers on, I flip the swith and go down the halls, but i get to the door with the octopus on it but it doesn't open.
Am i missing something, or am i in the wrong place?

You're at the exit of Collasium (the "fake" entrance).

Go to the front of the main building (looks like a temple) and at the right front corner as it faces you, you'll see a hole...swim down through there. That's the real entrance.

Cheers,

-Sazerac

Confused..lol So it's mot the one with 2 chests infront of entrance, but i have to swim down through the top of building right? Where is the switch then? Spirit eye can't pick it up, nothing is in that room, not unless i'm blind..haha
Thanks, i'll try one more time

Show,

It's the 3rd building - the one with the broken doors and columns. Here's a link to a picture of it. And the entrance itself.