You begin outside on a small plateau overlooking two areas on opposite sides. Also there's a third area nearby with a portal returning to Shadow Wood and a teleporter destination. In one area the plateau looks over is a small cave entrance with a dropoff just inside. When you step up to it, a flock of bats flies out and away.
Caverns[edit]
Junp down inside the entrance--it's just a short drop--where there's a low-ceilinged cavern with routes to the left, ahead and to the right. The right-hand passage leads down to another similar cavern with an exit leading outside. In this cavern is a passage to the left that dead-ends in a wall made of more colorful stone. This is actually a barrier that will be opened later. Just before here is a doorway to a deep cavern with a waterfall to the left and another entrance higher up on the opposite wall.
There's a well-hidden secret room in this area. In both this passage and the right-hand passage coming down from the first cave, look for sections of wall with a texture that looks like stalactites, one section in each passage. Both of these are revolving doors that spin when you activate them. They connect to a small room with an enemy and items.
Take a look outside: a network of narrow walkways divides the area into three very deep pits. When you go up the first walkway, look over the edge to your left, and you'll find a small ledge just below, where there's a Porkalator. At the far side of the outdoor area is a room with items and a teleporter. This goes back to the portal near where you entered the level, and is the exit from the cave system. You can also attract the attention of a few Afrits down each pit.
Left area and Horn Key side area[edit]
Back in the first cavern, take a look at the middle and left passages. The middle one leads past a route to the right that dead-ends at another colorful-stone barrier. The main passage continues past a stream and down to a long cavern with a pool and a steep stairway leading up to a third colorful-stone barrier.
Back in the first cavern, take the left-hand passage. A short ways inside you'll pass a small room of colorful stone to the right, with steps or platforms at the back and a Brown Serpent. Remember where this is; you'll need to return here shortly. Farther down the passage, to the left is a side route that doubles back, leads up and ends at a door needing the Horn Key. This goes directly to a small room with this part's puzzle-piece lever and a portal to Wastelands. The main passage continues to the same long cavern the middle passage led to. At the other end is a passage to another still-lower cave. In here is a waterfall and small pool.
Cave Key and upper caves[edit]
Go back to that small side room in the left-hand passage from the first cavern, that has the steps. In here, over to the left, look for and jump down a small hole in the floor. Inside this small room, step into the pool, and a hidden door connecting to the middle passage from the first cavern opens. Those three colorful-stone barriers are now open. All three lead to a large upper cavern, where you'll find the Cave Key. A passage beyond here continues up to the final, uppermost cavern.
In here is the source of the river that leads to the waterfall above the pool. To the right, near the river source, is a door needing the Swamp Key. In the cavern, a passage to the right goes past the upper entrance to the deep waterfall cavern, and ends at a pit in the floor that drops down to the cave near the outdoor area. (It's high enough to cause falling damage.) Back in the uppermost cavern, you'll see a Platinum Helmet in an alcove. Be careful: it's booby-trapped. The ceiling drops down in increments when you get near; it'll crush you if you step all the way inside. But if you carefully inch forward just to the point where you pick up the item, you won't trigger it.
Swamp Key side area[edit]
Past here is a winding passage leading up, with a side passage leading down. At the end of the side passage is a small room with this side's puzzle-piece lever. At the top of the main passage is a portal to Darkmere.