IMPORTANT: If you're hunting achievements/trophies, save the game before entering the dark cave and do not overwrite this save until you clear this area. (You can save in new slots as you go.) For the "Silk Cave" achievement/trophy, you'll need to "clear the spider cave without a scratch using only Lara's guns." This means pistols only, no damage. You may want to start with full health, so it'll be easier to tell if Lara has been bitten. There seems to be some confusion about this, but based on my playtesting, its OK if you happen to be bitten by the small spiders earlier in the level. Only the ones in this area matter.
I apologize for the state of these screenshots, but I wanted to make things as clear as possible, but this section is very dark. There is no in-game gamma control, so you may want to turn up the brightness on your TV or monitor in order to see where you're going—and conserve flares. You can also fire pistols repeatedly for light.

In the last section, we used the GOLD KEY and made our way through some flooded tunnels to this large cavern. Enter the dark, web-spangled cave with guns drawn. (Lara is able to spot those spiders better than you can.)

There'll be 2 small spiders (21-22) to start—one just inside the tunnel...

...one at the first corner, where the tunnel widens and turns left.

Beyond the bend, approach the flares (31) on the ground.

Two more spiders (23-24) drop down from the alcove on the right. Kill them then take the flares.

Turn so the alcove is behind Lara and advance slowly toward the alcove on the other side of the cave.

Two more small spiders (25-26) drop down there. Shoot them as they approach.

Now turn right, so the alcove where the last pair of spiders came from is on Lara's left. Move down the path into the open area below just far enough to trigger the appearance of a giant spider (27) in the opening ahead on the left.

Then hop back up the path shooting. (It takes about 45 pistol rounds to put it down.)

When the giant spider is dead, grab the Uzi ammo (32) lying on the ground in the far right corner.

Then approach the opening where the giant spider came from. Another small spider (28) drops from the alcove to the left of that opening. Kill it and proceed.

Enter the tunnel where the giant spider came from. A little way in, another giant spider (29) will drop from the ceiling of the tunnel. Stand in the position shown above, so Lara is roughly in the middle of the path, angled slightly to the left. Side flip to the left to spawn the spider. Then immediately flip back to the right...

...and backflip all the way into the cave while firing. (Otherwise, you run the risk of being pinned against a wall by the spider.)

When it's dead, return to the tunnel and follow it to an opening overlooking a cavern with a huge, glowing egg sac. (Saint Lara preserve us!) As soon as you hop down off the ledge, another giant spider (30) drops from the ceiling ahead on the right.

Shoot it as it moves toward you and/or backflip onto the ledge and continue firing.

The fourth giant spider (31) drops from the ceiling as you approach the far side of the cavern. So light a flare and run forward past the tall, angled pillar. As you near the far wall...

...roll and run back to the entrance. Jump up onto the ledge ...

...and shoot the spider from relative safety.
DARK MODE: I plan to add optional dark mode for these pages, but my current priority is updating the walkthroughs. Meanwhile, may I suggest a reputable dark mode browser extension, such as Dark Reader? (Download only from trusted sites, like darkreader.org or your browser's official add-on/extension site.)
Walkthrough text and diagrams copyright © Stellalune (email ). Feel free to copy or print this walkthrough for personal use. By all means, share it with friends, but please include this credit line so people can send me their feedback. No part of this walkthrough may be reproduced on another site without permission.