Just inside the "Restricted Area" door, the current will carry Lara along to the top of the passageway.

Notice the opening on the left leading into the underwater cave, but don't go that way yet. Instead surface in the yellow room at top of the wide passageway....

...and climb out of the water into a corridor with bars at the far end.

About halfway down the hall on the left is a room with a window and a locked door. Draw pistols and make some noise to get the attention of the gunman inside.

Kill him when he opens the door.

Go in and pick up a small medi pack and flares inside on the right...

...plus a bunch of harpoons behind the big screen. Hop over the trapdoor in the middle of the floor to open it, but don't drop through yet.

Press the button to open the bars at the end of the corridor. Exit the way you came in, turn left...

...then left again, into a long, enclosed walkway overlooking the sea floor.

At the end of the walkway, pick up a rocket and a small medi pack—and get a glimpse of another rocket and the goings-on inside the RESEARCH LAB.

NOTE: If you don't yet have the ROCKET LAUNCHER, you'll get it here.

[Part 2 | Return to the Sleeping with the Fishes Walkthrough]