Pull the switch again to return it to the up position. This resets the water levels to the way they were before (i.e., tank #1 half full and tank #2 empty).

Now go to tank #1, halfway down the long corridor.

Jump into the water and and swim down through the hatch you just opened. (It's just below the entrance, on the right.)

If you keep the blue lights on Lara's left as you dive into the hole, she'll be facing in the correct direction as she enters the flooded tunnel below.

Swim along the bottom past the huge propellers. As long as you pulled the switch to lower the water level, they'll be moving slowly enough so you can pass safely.

Surface beyond the second propeller and climb out of the water on the left, where the ledge is a little lower.

NOTE: If you're low on health or just don't care about getting all the kills, you can pull up at the middle of the ledge, where it slopes upward. As long as you don't step on the leftmost square, the next guard won't appear. Thanks to Kenny for this tip.

If you do trigger the guard, he appears in the hallway on the right.

Follow the passageway to the crawlspace on the right. Ignore the box of shotgun shells at the end of the hallway for now.

Shoot the 2 rats inside the crawlspace. Then pick up the shotgun ammo and crawl into the tunnel with the dead rats.

About halfway in, the ceiling is a little higher so Lara can stand again. Pick up the small medi pack here and continue to the end of the tunnel.

Drop in to the passageway below, and follow it to the next room.

[Part 1 | Return to the Thames Wharf Walkthrough]