One of the earliest side quests available in Horizon Forbidden West is “Deep Trouble,” a mission that sends you into mines to free a pair of stuck workers. Our Horizon Forbidden West Deep Trouble side quest walkthrough explains how to swim through waters, blow up the minecart, and save the two workers.
Shortly after picking up the side quest in Chainscrape, you’ll need to head to the Crimson Narrows to talk to the foreman, Korvend. He’ll say that the nearby mine collapsed, and two of his workers are stuck inside the flooded area.
To find them, you’ll need to swim and dive under the water to get through the wreckage. You can press the Square button to dive deeper and hold down the X button to come up for air. You only have so much oxygen, so you’ll need to watch that bar to make sure Aloy doesn’t drown.
After picking up some fuses from the stuck miners, you’ll need to follow the quest marker to dive back into the water and resurface. From here, there are obstacles for Aloy to climb above the water on. Use your Focus to highlight them for an easy climb.
The next room will have three Burrowers roaming around and Aloy will note that you can swim under them to avoid having to fight them and fire arrows at special mushrooms to create stealth zones. We found it easier to climb out of the water behind the enemies and just beat them mercilessly.
Keep following the path marked by the quest marker until you see a ladder to knock down. Kick it down to be able to access the area easily (if you fall) and use your Pullcaster on the nearby blue crosses.
Once you pull the crane over, jump on top of it and climb straight up the tracks to the minecart. Press Triangle next to the card to detonate the explosives.
A short cutscene will play as Aloy successfully drains the cavern, but three more robots will pop out. You can choose to ignore these if you want, but all early XP is good XP.
Use the Pullcaster again on the boxes blocking the exit to open up the path. Talk to the duo again and head out of the mines. Korvend will reward you with two Skill Points, 1,260 XP, and Oseram Artificer Face Paint.