- 1. As the group follows the sewage flow, there will be a few enemy encounters, including Grabbers, tentacle-like creatures that try to grab Nathan and bring him to them so they could kill him off. Shoot any Grabbers you see in their heads (one hit with the Plasma Cutter does the trick).
- 2. Text Log #1: After killing the first Grabber, the group goes down the tunnel. Lexine gasps at a falling object, and then Nathan turns towards a locked door up on a platform. Shoot the air vent above the lock door and grab the Text Log before he moves on.
- 3. When Weller talks about the exits being locked down there is a Line Gun on the platform to the right. The Line Gun is to the left of the locked door.
- 4. The path eventually forks, though both routes will take you to the center area for a big brawl. If you went left, there will be Grabbers, Exploders, and Slashers, while right has you fighting more Enhanced Slashers. There's plenty of Green Canisters to open here; it'll be helpful to hurl them into baddies using Kinesis for quick kills.
- 5. Both paths will end up in a sewer tunnel with loads of Exploders and Slashers charging ahead while "Lurkers" (baby-like creatures with tentacles) are flinging projectiles at you from the above catwalks. Firing them back with Kinesis is advised.
- 6. Nathan can grab an Arc Wielder after the fight; do so if you are low on your primary weapon.
- 1. After the cutscene of the worker getting killed, wipe out the Enhanced Slashers and the Infectors. Enhanced Slashers can take a lot of ammo before they go down, so try one-hit killing them with a Line Gun blast to the shoulders. Nathan will Free Look afterward, allowing you to blast open Green Canisters for supplies.
- 2. Lexine will fall into the water and be swept away, and the group must find her. Watch out for enemies as you progress. After killing the first group, you can grab a P-Sec Pistol on the platform above and to your left, where a Lurker was attacking.
- 3. Weapon Upgrade #1: After the catwalk with the P-Sec Pistol are two platforms to your right with two locked doors (a lone Leecher attacks right before it). Shoot the air vent above, before the group goes left into the dead-end.
- 4. Weapon Upgrade #2: Yet another Weapon Upgrade hidden in an air vent, almost right after getting Weapon Upgrade #1; this time it's in an air vent above the platform with the propped-up headless corpse that startles Eckhardt.
- 5. The path continues into a dead end, then back towards a catwalk the group must climb. There will be two groups of Enhanced Slashers and Grabbers, as well as Female Slashers and Lurkers on catwalks. Headshot these Females for an instant kill and remember to hurl away incoming projectiles with Kinesis.
- 6. After killing the second group of enemies, Nathan and co. will enter a new area. You can grab a Force Gun when Nathan turns right after entering.
- 7. The room is flooded with gas; you must quickly win a Hacking Mini-game before the gas takes effect. Afterward, Nathan and co. will drop down.
- 8. Audio Log #1: You can see the Audio Log underneath the catwalk mesh after winning the Hacking Mini-game; you'll be able to grab it after Nathan drops down into the water and turns to face it.
- 9. Afterward, Nathan and co. continue. A Lurker will appear and, despite it actually being an illusion, you must kill it quickly anyway before it can pile on damage.
- 10. Weapon Upgrade #3: It's in the air vent above the Lurker hallucination. Shoot the Lurker, then the vent, then the Lurker, then grab the upgrade, then kill the Lurker.
- 11. Keep going and you'll hit a fork. Doesn't matter which way you go either as the left path is a dead-end anyway, and the group will eventually go route.
- 12. Weapon Upgrade #4: As usual, shoot the air vent above the elevated platform, in this case, the one before the platform holding the Contact Beam.
- 13. As the group travels along the right-hand route, Nathan will eventually spot a Contact Beam after cutting through some growth; you can replace the Line Gun with this if you like although the other will be useful against the incoming boss.
- 14. Ahead is another Lurker and Slasher ambush. As always, use the Lurker projectiles against the enemies.
- 15. Text Log #2: Grab the Text Log on the console behind this Lurker.
- 16. Text Log #3: Past the platform with Text Log #2 is another platform with a load of Green Containers. As always, shoot the air vent above it.
- 1. Further ahead you will reach a vast room, with a new character above you, Karen. She will flee when a boss creature attacks, called "The Slug".
- 2. For the first phase, the key is to shoot the yellow weakpoints on the tentacles when they appear with a ballistic weapon such as the P-Sec Pistol or Pulse Rifle. A few other weapons like the Plasma Cutter and Arc Welding Gun will also work, and if you don't have any that do, you'll probably need to use the Rivet Gun, which can be a bit of a pain. Shoot the weakpoints enough and Nathan will run over to one of the two fans in the room.
- 3. Keep shooting the weakpoints until Nathan can Free Look; turn towards the spinning fan blades and use the Stasis Module on it to slow them down. Nathan should slip past the slowed fan if you are fast enough, which causes a tentacle to get chopped up when it tries to pursue him. He'll then return to the starting point; you'll need to repeat the above steps again, more times if Nathan fails to slip past a fan quick enough before returning to the starting point.
- 4. Weapon Upgrade #5: It's on the catwalk where the right-hand fan is. Grab it during the Free Look before dealing with the fan.
- 5. Next, fuel drums will appear in the water. Nathan must grab them with Kinesis and hurl them at the last two tentacles. If you aren't quick enough, they will try to drag Nathan into The Slug's maw. If that happens, cook its maw when you are in range with the Flamethrower for an easy escape; a few other guns such as the Plasma Cutter and Line Gun also work.
- 6. Finally, The Slug will hurl acid blobs while you must shoot the yellow pustule that wiggles back and forth. If you have the Arc Wielder, it will be a ridiculously easy win as this weakpoint is EXTREMELY weak to its primary fire mode. Otherwise, hurl the acid blobs back while you spam area effect attacks like the Line Gun's mines or the Flamethrower's Alt-Fire. It will spam the acid blobs quite a bit, but the Flamethrower will help you ward them off while you grab one safely.