From what I know (thanks to stella's walkthrough), apparently, "There's an underwater cave in the cliff wall nearby. It's ahead on the right if Lara is treading water facing the ledge and cascade of water from above. You can spot it easily using the sonar map in Lara's PDA. This is the exit through which you return to this area at the end of the level. Do not explore there now. Some players have experienced a bug in which swimming too close to the closed doors at the end of the tunnel prevents the lever that opens the doors from the other side from appearing. If you've already done this, you may want to restart the level now to prevent potential problems later." (that's directly from the walkthrough btw. That's all I've got.)
Last edited by Derr403; 10-15-2009 at 12:50 PM.
Reason: spelling errors