~ COOLING FACILITY ~

Head forward and drop into the pipe. Follow it outside and destroy enemies. Use barrels to get onto a crate with a Chain Gun. Press the button on the wall to open the floor beneath you.

Go up the stairs across from where you started the level and follow the corridor to more stairs. Head up them and clear the area.

Drop into the hole you just opened to enter a sewer. Avoid the strong current in the water.

Walk along the outer edge to the left to enter a circular room with Stimpacks and Armor Shards.

Walk along the left edge of the waterway and round a corner. Slowly walk down the incline and climb down the ladder on the left for a secret area with Adrenaline.

Climb back up the ladder and go down the incline to a room full of ammo and enemies.

Continue down the waterway to a large pool with moving platforms. Go up a platform and defeat the Berserkers.

Go through the doors to enter a large room with a big pipe. Turn the valve on the pipe to complete half your secondary objective.

Climb onto the crates and jump onto the moving platform in the pipe. Ride it up.

Jump to the button across from you to complete your secondary objective. You will be given a new objective: return to the Reactor.

Next to the button are crates. Climb onto them and then jump onto the piston moving up and down. Jump onto the next one.

Follow the corridor up to a platform. Hop on and ride it up.

Follow the waterway to a familiar area near the start of the level. Head forward and drop through the hole in the floor.

Go through the door to return to the Reactor. Head forward and drop through a hole. Your secondary objective will update, and you need to go to the Toxic Waste Dump.

Go through the corridor on the right, past the reactor core, and keep going straight to enter a large outdoor area.

Find the BFG on the right. Go into the pipe on the left and follow it to a hole. Drop into it to enter the Toxic Waste Dump.