After opening the pit in the floor and following the ROCKY TUNNEL to the TALL ROOM WITH STAIRCASES AND POOL, as shown in the previous section, take a standing jump onto the ledge to the left of the entrance (or run carefully across the gap at the left corner).

From here you can see a large medipack in the hall leading off to the north. This hallway is fire-trapped, so avoid it for now. Instead, climb onto the ledge on the left (i.e., just above the stairs leading down).

From there, take a running jump to the stairs along the west wall. Go to the top of these stairs.

Turn left and jump to grab the ceiling. (This texture looks a little different from the usual ceiling bars, but it works.)

Monkey swing to the small opening in the south wall.

Position Lara right up against the wall, then let go and quickly press Action again to grab the edge of the opening. Pull up and crawl inside.

This is SECRET #1 (61/70), a large medipack and flash grenades.

Climb out the way you came and drop into the pool below.

Roll and swim through the opening on the right into the pool below the entrance.

Ignore the opening on the bottom of the pool for now. Instead, pick up some super grenades on one of the underwater ledges in the southeast corner. Then climb out of the water onto the long ledge along the east wall.

Take a running jump to grab the block ledge on the west side and pull up.

[Citadel Walkthrough]