Getting the Blue Key (4)

Enter the acid and follow the current through the pipe. On a ledge to the left within the pipe, find a Large Medikit and a Trooper.

Upon exiting the pipe, you can go left or right.

Left Ramp: Follow the ramp. You will fight a Captain. Find Pistol Ammo and a Shotgun at the bottom of the first ramp. At the bottom of the first ramp, you can fall off to a platform with an Octabrain (good for Pipebomb), a Large Medikit, and a clip. The second downward ramp leads into acid, potentially taking laser fire from a Mounted Gun.

Right Ramp: You will encounter a Trooper and a Small Medikit. Continue to a door; inside is another Trooper, Shotgun Shells, and Protective Boots. Facing the door, look down the left ledge to find a platform leading to the Blue Key door. Before dropping, eliminate a Pig Cop and an Octabrain from your current position. On the platform, grab an RPG. Through the Blue Key door, a Pig Cop is visible; it can be killed with a Pipebomb without it being able to attack you.

The Big Fork: After dealing with the Blue Key area, enter the acid and follow the current to a large rock formation. You have three paths: left, right, and center. Two Troopers and Chaingun Cannon Ammo are to your left where you emerge. The Center and Right Paths are optional.

The River (Optional): Following the acid river to its end leads to a platform with Protective Boots, a Holoduke, and a Portable Medikit.

Right Path (Optional): This path starts with Pistol Ammo. Continue to find a Pistol. Jump to elevated ground where you must fight two Troopers. In this clearing, find Night Vision Goggles, two Pistol Ammo, and two Large Medikits.

Center Path (Optional): This path consists of two ledges: the left has a Large Medikit, and the right has Shotgun Shells.

Left Path: Start on a ledge and follow it to find a Large Medikit and a clip. Destroy a cactus and defeat a Trooper on a higher ledge. At the end, you will find the Blue Key, two boxes of Shotgun Shells, and a Large Medikit. Look behind you to see a broken bridge above with a Trooper at the end.

Down Left Path (Optional): Near the left path, find a canyon. Follow it down to get Chaingun Cannon Ammo and a Large Medikit. At the canyon's end, a hole in the wall contains an Octabrain and a Chaingun Cannon.