Relic Ruins: The Stillsands is a collectible in Horizon Forbidden West. This walkthrough will guide you through all steps of The Stillsands Relic Ruins.
Location – Relic Ruins: The Stillsands
Walkthrough – Relic Ruins: The Stillsands
Step 1: Start in the north of the ruins and enter the broken wall of the ruins. You can use the rubble around the ruins to climb up. Drop to the bottom of the ruins, can use paraglider to avoid falling damage.
Step 2: In the north-west corner of the ruins is a firegleam, destroy it. Behind it you find a crate.
Step 3: Push the crate under the yellow ledge. Climb up.
Step 4: Use the yellow valve. This will cause water to flow in from the pipe but it’s going in the drain. To plug the drain you must push the crate in front of it. Then the water level will rise.
Step 5: Swim to the south-east corner of the ruins, there you find the Key Module for the storage room, pick it up.
Step 6: Use the key module to open the storage room in the north of the ruins. This reveals a second crate.
Step 7: Push the second crate out of the storage room and drop it in the water. Your goal is to get it to the opposite side of the ruins (south side), then you can climb the crate in the water and from there jump to a yellow ledge that lets you climb up to the relic. Getting the crate over there requires using the pullcaster to pull it from one point to the next ( 
+ 
> hold 
).
Step 8: First, stand at the bottom of the climbable pillar, straight ahead of the storage room. Pull the crate there. You can’t push the crate in the water, you can only pull it while standing on solid ground outside the water.
Step 9: Second, swim to the next pillar (south) and pull the crate there. It sometimes gets stuck behind the first pillar, just try a few times until it gets unstuck.
Step 10: Third, switch over to the other side and pull the crate there.
Step 11: Fourth, go all the way back in the corner at the south-end of the ruins and pull the crate towards the yellow climbable ledge at the end of the path.
Step 12: Now you can climb the crate and from there jump to the yellow ledge, climb up and you’ll find the relic ornament.
This finishes Relic Ruins: The Stillsands in Horizon Forbidden West.
For all other Collectibles and Quests, check out the full Horizon Forbidden West 100% Completion Wiki.
There is no crate for me behind the red gleam wall.
edit : There is however a crate up the slightly curved staircase that I could drag into the room to block the drain. Thankfully the crate behind the key door was there to use in getting the relic. Maybe they changed the location of the crate in a patch.
Spent more than an hour trying here was no way to do this, could not get pullcaster to attach for the final pull. So i ended up removing the first crate to drain the water, then placed the second crate where it was needed, then flooding the place again.