Bus Depot: Underground Tunnel

Head through the bus and hop out of its window. Head down and check the wheel of the green car near the bus to find [2 ARROWS]. Check behind the bus on the road to find a [FIREFLY PENDANT (NATALIE HOO)].

Enter the tunnel and move over the truck. In this area, search the walkway to the right to find [(1/4) ALCOHOL] near a truck. Look in the far left corner of the walkway on the left side of the tunnel to find [10 PARTS], [(1/2) BLADES] and [(1/4) RAG].

Tunnel Stealth Approach

The next area contains several infected; a Bloater, three inactive Runners (more like 'Standers'), and a Clicker. Stay on the right side of the tunnel. You can take out the two nearby Runners with stealth strangles, but you'll have to approach them VERY quietly, and the one in the middle of the tunnel is best approached by hugging the wall while staying as far away as possible from it until the triangle button prompt appears. An alternative stealth takeout can be done with arrow headshots. With these two out of the way, leave the others alone and sneak further down the tunnel.

Search the right side of the walkway to find [50 FLAMETHROWER FUEL]. The room to the right contains [(1/2) ALCOHOL], [(1/2) EXPLOSIVE], [(1/4) BLADES] and [3 PARTS]. There are three Runners in the hall up ahead. The first can be strangled by approaching it very quietly, but it doesn't seem to be possible for the other two, so you'll want to down them with arrow headshots, or, if that's not an option for you, with melee attacks; if done correctly, the attention of any other enemies is not drawn. You could also choose to sneak past them by moving through the other hall. Search the room up ahead for [(1/4) BLADES], [25 PARTS] and [(3/4) BINDING].

Note: You can find the [BOMB: PROXIMITY MINES (TRAINING MANUAL) from the top of the truck on the left side in this area. You can sneak towards it, or alternative you can try clearing the area first.

As you move further down the tunnel you'll spot two Bloaters, two Clickers and two inactive Runners. Search the walkway on the right side of the tunnel to find [(1/4) ALCOHOL], a [RAG] and [2 EL DIABLO AMMO] at the end. It's advisable to sneak past these infected. The best way to do so is to move to the end of the walkway you're currently at (where you found the above items), wait for the roaming Clicker to move away to the left side, hop over the walkway railing, sneak towards the two Bloaters and quietly climbing the car wreck behind them, hugging the rock wall all the time, then quickly continuing down the tunnel. Boost Ellie up and she'll drop down a crate for you, allowing you to move over.

In the next tunnel, swim underneath the truck at the end and lower the ladder for Ellie at the yellow lines of the walkway. Move over the upper left air ventilation walkway to reach the [CATALYSIS] comic. Head down and check the corner of the walkway to find [5 REVOLVER AMMO] next to the skeleton. Inspect the door, then boost Ellie over to the left side and kill the Clicker. Search the room for [(1/2) BLADES] and upgrade your weapons at the Workbench if you wish.

The closed storage room to the right requires a Shiv to open; inside you can find [10 SKILL PILLS], [50 PARTS], [(3/4) EXPLOSIVE], an [ARROW] and [(3/4) SUGAR]. When you reach the reservoir, dive in, take a deep breath and move through the doorway, go around the right corner and swim to the far end to reach a new room. Here climb up to reach the ventilation shafts and make your way to the upper catwalk, where you can drop down the raft to get Ellie across. When the ladder breaks, place it against the wall so you can reach the upper walkway again and take it with you to the other side to create a bridge.

In the next tunnel, move over the improvised walkway until Joel falls into the bus. Press triangle to move forwards, then try to get out; after this, quickly swim over to Ellie and swim to the surface to trigger a scene.