To complete Relic Ruins: Isle of Spiers in Horizon Forbidden West, you need to find and enter a 7-digit door code to gain access to the ornament in the locked room. You have to explore the entire ruin and solve different puzzles to find all the pieces of code you need.
Climb the pillar in the middle of the flooded ruins, then use your grapple to get to the higher floor. Use your grapple to get to an even higher floor, then jump off the end of the yellow bar and use your mid-air grapple to get to the east side of the ruins. If you look back you will see a box. Use your pullcaster to pull it into the water below, then drop down.
Climb out of the water onto the ground east of the crate, then use your pullcaster to pull the crate out of the water. Drag it under the hatch, then use your pullcaster to open the hatch, climb onto the crate, then climb up through the hatch. Crawl out of the opening and then climb onto the floor above. Go through the gap to the south and use your Focus to read the Locked In! data point. It asks you to start with a 2 and then just press each number counter-clockwise, meaning the code is 2109. Go back to the north room and use this code to open the door.
Related: How to capture the Isle of Spiers Survey Drone in Horizon Forbidden West
To find the second part of the code, start by the campfire outside the northeast corner of the ruin. Climb up the outer wall, head west into the building, and go around the corner past the cylindrical device marked with a battery icon (it’s a charger, but not the charger you need to use). Use your pullcaster to open the overhead hatch and climb up. Drop into the space at the far end of the opening and ignite the fire brilliance.
Exit through the hole, turn left and left again, and remove the glowing power cell from the wall. Take it back to the fire shine room and place it in the charger. Wait for it to charge, then remove it and take it to the elevator on the east side of the floor. Turn on the elevator and then go to the bottom floor. Use your pullcaster to get the crate out of the water and drag it into the elevator. Take the elevator back up, then drag the crate to the location in the screenshot below. Climb the ledge and then jump over to the other building.
Go through the crack in the wall to the south office. Use your focus on the datapad on the desk and it will tell you that the access code to the office building is 1 – 0 – floor number. The title of the data point is Security Measures on the 9th floor, so the code for the door in this room is 1-0-9 (it’s also the second part of the code you need to get the ornament). Enter 109 on the console in this room to open the door.
You now have both parts of the Isle of Spiers Relic Ruins door code, which is 2109109.
https://doublexp.com/guides/what-is-the-isle-of-spires-relic-ruins-door-code-in-horizon-forbidden-west What is the Isle of Spiers relic ruins door code in Horizon Forbidden West?