Plumbing the Depths is the 19th Main Story Quest of Dead Island 2, and it's a bit of a confusing one. At first, it seems simple, one of the Serling Hotel survivors by the name of Bob has gone missing while trying to get the water turned back on, so it's up to the player to find him and finish the job.
But, actually figuring out where to go, how to advance through the Quest, and where to find Bob is a bit more involved than it first appears. Granted, this is a Dead Island 2 Main Story Quest so players will need to do it at some point unlike with Side Quests. But, it's still helpful to know exactly where to go and exactly what to do.
Find The Janitor's Office & Pin Down Bob's Location
First things first, players will need to actually grab this Quest from Denise, the guard of the entrance to the Serling Hotel Safe Zone. She'll mention that the water is off and that the janitor they sent down to fix it, Bob, hasn't come back in a while. So, from here, players need to head down to the bottom-most floor of the Lotusville Mall that's connected to the Serling Hotel and look for the Jewelry Shop with the half-closed entrance gate. To be a bit more clear, it's the shop directly to the left of the 'Safe' sign that points to the stairway to the right. Crouch/slide underneath the gate and head to the room in the back that connects to the Maintenance Corridors for both the hotel and the mall.
Turn to the right, walk forward a few steps, then go through the door to the immediate left (while ducking under the tripwire). In here are a few objects players will need to grab before the 'Where the hell has Bob gone?' objective gets to 100 percent:
- Grab the document on the table directly ahead AKA the Note for Bob.
- Climb up onto the vending machines on the right-hand side of the room and then look at the pipes on the ceiling to see the Janitor's Office Safe Code.
- Take the Code and use it to unlock the Janitor's Safe in the back-right corner of the room and get the Plumbing Schematic.
From here, players will need to head toward the Boiler Room in the basement of the Parking Garage for the Lotusville Mall.
Explore The Parking Garage & Kill Em' All
After getting the Plumbing Schematic, head out of the Janitor's Office, turn left, and follow this corridor around until it has the player going down some stairs and ending up in front of an openable door with a large 'A' on the wall to the left of the door. Open the door to get out into the Parking Garage. From here, players can then follow the Garage upward to interact with the Security Keypad to open up the gate so that they have an exit later, or they can head down and use another Security Keypad to open the gate blocking their way and worry about finding an exit after.
Follow the winding path downward to the next level of the Parking Garage, and players should come upon a large open room with a plume of flame coming out from a pipe on the right-most pillar. Walk further into this room and the Quest objective should change to "Kill em' all!", and that's exactly what players need to do. Groups of Zombies will slowly spawn in alongside the group already in the room and players need to take them all out.
The majority of these are basic Runners, Shamblers, and Walkers (of all different types, of course), but there's also a Screamer Apex Zombie mixed in as well. After clearing out a whole slew of Zombies here, the objective will change to 'Bob?' and players will want to head to the only door in this area, which is the Boiler Room. Additionally, the Scream Ability Skill Card should unlock for all players here as well as soon as they take out the last Zombie.
Kill Bob & Turn On The Water
Sadly, like most of these Quests where the player hunts down survivors in the 'hopes' that they're still alive, Bob is unfortunately already a Zombie and will grapple the player as soon as they open the Boiler Room door. Bob is a Named variant of a Shocking Walker, but he's not at all difficult to take care of. After killing Bob and, albeit briefly, mourning his sacrifice, players will then want to interact with the Water Pipe Lever on the blue pipe to their right, holding down the input until it finishes. After this, just head back to the Serling Hotel by heading up the Parking Garage ramps out onto the street, turning right, and walking forward until the Serling Hotel building is in view on the right-hand side.
Head back into the Mall and climb back up to the Hotel to give Denise the bad news about Bob's passing. After this, Denise will mention that Dr. Reed is back, and players will need to interact with his door and get through that whole cutscene before the Quest is officially 'finished'.
Plumbing The Depths Quest Rewards
After talking with Dr. Reed and pushing the plan forward by getting ready to go to the CDC HQ near the Santa Monica Pier, the 'Story Quest Complete' message will pop up. As a reward, this Story Quest gives 4,000 EXP as well as the CDC HQ Security Pass (needed for the next Story Quest) and the Hot-Footed Skill Card, which is an Autophage Skill that gives the Drop Kick the ability to Ignite Zombies on contact.
Dead Island 2 is available now for PC, PS4, PS5, Xbox One, and Xbox Series X\S.