In Utopia, you will find a device that requires a harpoon and a carbon dioxide canister.
This device is at the top of a building, after you climb a winding staircase.
Here’s how you can get a carbon dioxide canister and a harpoon in Raft.
How to get a harpoon
To get a harpoon, you need to find all 3 Detto’s Code. You can use the guide on how to find Detto’s Codes.
After getting them, unlock the door and enter the house.
You should find a harpoon at the side of the room.
How to get a carbon dioxide canister
The canister requires you to find electricity and connect the water pipes to the tank.
You can use the guide linked above.
The water will eventually flow to the water tank, and the carbon dioxide canister will float. You can pick it up from the top of the tank.
Once you have both items, go back to the device and fire the harpoon to the next building marked “X”.
You can zipline to the building and look for the entrance key.