Part 13

From the previous area, blast enemies with the shotgun and run along the path. Find a small cave with a lone Houndeye (use the crowbar) and a spiky plant next to a vine-covered tunnel.

Quicksave. Crouch-walk along the wall to the right of the tunnel entrance to avoid the spiky plant. If spiked, quickrestore and try again.

Bash the vines with the crowbar and enter the tunnel.

Move along the tunnel to another small cave. Bash the vines and find two vine-covered tunnel entrances. The one with a spiky plant nearby is your target.

Quicksave. Crouch-walk to the wall halfway between the two spiky plants, turn left, and crouch-walk to the tunnel entrance.

Bash the vines, then move forward slowly with the flashlight on and pistol out. Sneak-shoot the two headcrabs past the tunnel curve.

Continue past the headcrabs to a two-way tunnel split with another headcrab. Take the left branch first and sneak-shoot the headcrab. Grab the ammo canister from the dead HEV guy.

Return to the split and take the other (straight ahead) path. Sneak-shoot the headcrab after the tunnel turns left.

Go past the headcrab to bashable vines leading to another small cave. Crouch-walk slowly into the cave, looking right, to spot and shoot a headcrab on a rock.

Quicksave. Go to the rock where the headcrab was. Move to the small tunnel on the opposite side of the cave where a Bullsquid is located.

Quickly turn left and run to the spiky plant against the left wall. Crouch behind the plant so it's between you and the Bullsquid. Wait for the Bullsquid to kill the other headcrab.

If the Bullsquid ignores the crab or runs to your side of the plant, quickrestore and try again. Once it's on the other side of the plant, hit the plant with the crowbar until it kills the Bullsquid.

Jump onto the rock where you shot the first headcrab. Crouch and enter the tunnel after bashing its vines.

Shoot the headcrab ahead with its back turned. Move past it to find another turned-around headcrab in a small cave.

Go around the cave's central pillar to a path split at a large yellow crystal. Go straight.

Shoot the headcrab past the next tunnel turn. In the cave at the end of the tunnel, kill the two headcrabs (one to the right) and grab the ammo canister from the dead HEV guy.

Return to the cave room where you found the Bullsquid. Use the left tunnel (top of a short rocky ramp) to proceed.

Soon after entering, shoot the headcrab in a small cave ahead.

Get out the crowbar and quicksave. Run into the cave to make another headcrab drop down. Whack it to death without taking damage (quickrestore and try again if needed). Alternatively, shoot out the vine "grating" in the ceiling to make it drop early and shoot it before it leaps.

Move along the tunnel until it splits, turn right, and keep going until you reach vines.

After bashing the vines, get out the pistol and shoot the headcrab on the other side of the large pool. Use the flashlight to help.

Crouch-strafe to sneak-shoot another crab just to the right of the tunnel exit.

Exit the tunnel and stand in the healing pool. Dive into the big water pool and swim down to a rocky ledge on the right with a "plant light" and a dead HEV guy. Grab the ammo canister.

Lean on the "Swim up" key to return to the surface. Jump onto the pathway around the pool from a spot just to the right of the healing pool. Kill any barnacles with the crowbar.

To access Chumtoad's Lair: Get back in the healing pool, get out the crowbar, and quicksave.

Run from the healing pool into the big water pool, look down, and lean on the "Swim down" key.

Turn on the flashlight as you descend. Swim left toward a large rock. To the right of the rock is a crack in the wall leaking air bubbles.

Bang on the wall near the crack with the crowbar until it breaks open. Quickly swim into the tunnel, bash the vines, and surface.