If you swing over to the western alcove in the HUGE ROOM WITH HIGH PLATFORM, ROPES, AND SMALL POOL (shown above) and save the game, you will miss the first secret, since there's no way to reach the ropes and try again. However, you can do this by using the crawling corner bug. This maneuver is detailed in the Useful Bugs section, which includes step-by-step instructions and a video.

To get down to the floor, first grab the climbable wall at the back of the alcove.

Climb down and drop to the floor.

This stairway leads to the TEMPLE OF POSEIDON, which you're not ready for yet. So turn around and run across the big room to the base of the high platform.

Any of the corners on this wide, rectangular support pillar will work, but I do recommend saving again before you attempt this. Occasionally Lara will bug up onto the platform and then immediately lose her footing and fall. If that happens, just reload and try again, maybe with a different corner.

Here I'll demonstrate the bug using the back left corner of the pillar since it works consistently and the lighting is pretty good here.

Stand facing the pillar with Lara's left foot almost at the left edge.

Pivot about 45 degrees to the left, like you would for the basic corner bug.

Now hold Duck/Crouch. If Lara is positioned correctly, her right shoulder and knee will creep into the corner a little.

While still holding Duck/Crouch, press Forward once so Lara goes onto her hands and knees. Now Lara's upper body should disappear into the corner texture.

Release Duck/Crouch and she should spring up through the wall to land on the ledge above. Now you can use the 2 dangling ropes to reach the secret, as shown in this section.

[Catacombs Walkthrough]