Note: The caves are basically a simple maze and can be played using several different routes - notably crawling through the dark muddy tunnels to the left of the start point until you find the snake pit. This walkthrough allows you to pick up all the stuff but you don't miss much by taking short cuts!
As the level begins, you can go right or left. Head left for now. At the intersection, there are two dead-ends to the right and a crawlspace just to the left with a snake hidden inside. A little further along the corridor is another crawlspace leading to Uzi ammo and beyond these crawlspace entrances is a corner leading to a long dark corridor with a hole in the floor. The crawlspaces are linked and you can get through to the snake pit by following them - just don't get lost!
After looting the crawlspaces return to the corridor and head for the dark hole in the floor. Drop down it. At the bottom of this hole is another with a pack of flares on the floor. Double back to the beginning of the level. This time, choose the right-hand path. Crawl through to a spot above a long ramp. A boulder will follow you down. If you jump to get a head start on it at the bottom of the ramp don't jump from so high that Lara falls into a crouch. Sprint down the hall and make a quick left to avoid the boulder.
Down the next hallway, there's a niche on the right. You'll need to use that to escape from the path of another boulder. Go a couple of steps down the hallway and roll. If the boulder drops, run back down the hall. If it doesn't, venture a bit further and roll again. When the boulder drops, run back to the niche. Once the danger has passed, continue down the hallway. At the end there's a ledge you can jump up and grab.
Crawl through into the hallways beyond. To the left, walk cautiously around the corner. Pause to take out the snake and then return. To the right from the crawlspace entrance is the correct route. At the intersection which you'll soon double back to, take a right. Follow the hallway as it winds to the left. Grab the Shotgun shells. Now double back to that last intersection and head to the right.
Follow the hallway. At the slightly raised floor in the intersection, look to the left. Push the block there to open up a new corridor. Turn and head to the right. Go right again at the next intersection and follow the hallway. There are several short dead-ends, but only one long hall. At the end of the long hall, you'll find a hole in the floor.
Drop down the hole, and continue to follow the hall. Climb up the ledge at the end and crawl through to the intersection. Follow the hallway left from the intersection, and you'll find a room with a Save Crystal above a hole in the floor. Take the flares, and jump over the hole to take the crystal.
Prepare your flares for the next section! Hang and drop down the hole, and you'll land in the middle of four snakes. Dispose of the snakes in that half of the room (a medikit is likely to be prescribed!) and notice the two ramps further on. When you go near the ramps, a boulder rolls through the room but it's easily dodged. In the second section of the room, there are six more snakes to slay. After that, follow the hallway where the boulder made its exit, and crawl through the space.
Collect the Save Crystal and small medikit. Save the game before sliding down the ramp to meet the young hooligan from the previous levels. He makes quite a display upon your arrival - the water becomes lethal. The best strategy is to loose off several shots before the light display and edge to the left of the platform. Now leap from side to side shooting all the time and you should be OK. If you catch fire you've basically had it and the fireballs that are thrown at you bounce off the walls behind you, so missing them isn't that easy.
When it's safe, run and jump around the platforms, collecting the Grenade Launcher and refills. When you take the relic from the central section, the level ends and you're rewarded with a major movie. After that you get a choice of locations for the next adventure - I decided Lara needed a beach holiday and went to the South Pacific.
