Tomb Raider: Anniversary/Tomb of Qualopec

The Tome of Qualopec is the final chamber.

Entrance
After entering the waterfall, there are a few jumps to perform. The pole jumps are not dangerous and are straight forward. However, when you reach the middle chamber, the three porticulus will close, requiring you to open them. Each door has a symbol, that matches a symbol above the other three doorways.

First Portcullis
The first door is accessed by a switch above the first entrance. First, you need to move the platform to the left corner, and climb above the doorway. This lets you reach a grapple ring, while allowing you to get a clear shot on the tablet that is hanging in the room.

Shoot the rope holding up the stone tablet, and it will crash to the ground. This reveals a second platform (which isn't required to complete this level, but makes the jumps much easier). Now, you can use the two grapple rings to reach the switch above the first entrance, and open the first gate.

Second portcullis
Move the two platforms to the left, and follow the corridor. This will be a long series of jumps across a deep pit.

When you reach the switch chamber, the room was already collapsed. You can reach the switch by climbing the pole on the left (optionally using the grappling hook to first swing to the center platform), and leaping onto the horizontal bar. From there, you can grab a ledge and climb onto the upper platform.

On the return trip, you will be attacked by a dinosaur.

Third portcullis
Move the two platforms to the right, jump across and follow the corridor. (If you use just one platform, it needs to be precisely placed - it's easier to get two instead.

Follow the corridor, with a short wall-climbing adventure over a deep pit. When you reach the switch room and approach the switch, the ground will collapse, bringing you into combat with two wolves. Defeat them, and climb the ramp. Look for a cage below the entrance, and bring it down to the ground. Use it to climb onto a ledge found on one of the support pillars, in order to start a series of jumps to reach the switch.

Once you pull the switch down, continue to the right, and climb up. This brings you through a small loop that allows you to exit the third chamber.

On the return trip, you will be attacked by a dinosaur.

Escape
Once all three portcullises are open, you may proceed down the newly opened corridor. Once you collect the artifact in a cutscene, the cavern will begin to shake. Trace your steps back to the entrance of the tomb until you reach the waterfall. While there are monsters added on the return trip, none of them will interfere with your travel unless you miss a jump.

After exiting the tomb, you will receive the final cutscene for the chapter, where you need to press the appropriate arrow key to avoid an attack.