The Relic Ruins: Dry Yearn quest can be found in the central area of the map. It looks to be some abandoned tunnel or railway station on the side of a mountain. The relic is quite close to the entrance but out of reach, you must make your way around the interior of this structure to be able to claim the treasure.
To the top left, near the back wall, you will see a device that contains a yellow wheel that you can interact with. You will find a crate nearby. Pull it down and use this to climb onto the platform and interact with the control. This will cause the nearby door to lift, but it will only stay up for a short period of time. Quickly jump down and slide under this door.
At the back wall of this area, you will see a blue metal clamp that you can grab with your pull caster to reveal a train cart. Pull this cart toward the main blast door and use it as a platform to climb up to the nearby door and to the other platform to get the maintenance key.
Head through the door and go back out to the main room you started in. Use the same control as before and when it lifts up, use the train cart that is on the other side to block the door from coming back down. You can use your pull caster to grab it and pull it so that it sits in the middle of the doors locking mechanism.
Once the door is jammed, head inside and climb onto the rail cart trailer which will allow you to climb up the door and over to a nearby platform on the upper part of the room. This area was previously inaccessible to you.
Make your way through the nearby door and you will be able to look down off the ledge into the main room below and will see the relic sitting on the railing below you. Carefully drop down onto this and you will have completed Relic Ruins: Dry Yearn.