On this page of the Far Cry 6 guide, you will find a detailed description of the Liquid Courage treasure hunt in the Valle De Oro region.
District: Del Toro Port.
Start the task by reading the note that lies on the desk right at the entrance to the building.
Once you get to the next part, you will have to unscrew 3 valves. The first one is to the right of the door, you will notice it right away.
You have to get to the second one by walking on the pipes. They are set up so that you can go to the valve without any problems.
The last valve is located in the left corner of the room, right next to the huge tubs.
After turning all the valves, you will see the last one. There are 3 green lights above it (they should be green if you did everything right). Turn this valve when you are sure you have checked everything.
There will be an explosion that will allow you to move on. Look up at the ceiling and go up the rope. Keep moving forward until you reach a room where a dead man lies. There, the character will sober up - open the chests. You'll complete the mission.