There are mentions of Gwaithir in A Book on Indrin's Beacon, it "feels like" this could be the entrance..
> l
You now stand at the edge of the open desert. From here you can see far to the east, across the Sword Sea. To your north "The Great Volcano" reaches far up into the sky, looming dark and ominous almost as if it were forbidden ground. Looking around here, you realize that you are also at the top of a cliff face, and far below you the surf of the Sword Sea crashes in relentlessly against the rock strewn beach. All around you are scattered the building stones of a tower. What once must have towered over the coastal cliff, defending the coast, is now only a shattered ruin. Here the outline of its foundation can still be traced in the swirling sand. There is a large stone slab near the edge of the foundation. What appears to have been a wall that ran along the cliff's edge, now is little more than a ridge in the sand. Between the tower's fallen stones and the crashing waters below stands the remains of an obelisk. Crumbled bits of rock have gathered around its weathered base, and it seems to stand as reminder of times long ago forgotten. And the only thing that resembles a road, quickly tapers off to little more than a low spot in the sand.
...
→ gives you cliff exit
→ If Medium or short coil of rope, then cliff exit →
...
"chain dangling down over the lip of the cliff now just"
→ pull chain
Notes
- I believe this is the entrance to Gwaithir
- reading A Book on Indrin's Beacon it could be there is a hole to a chamber here. As Gelion is also mentioned with Gwaithir. I believe that possibly his rope tying skills are related.
- It could be that we need to tie the medium or short rope, then try hole or similar before we climb back up
Gelion
Same room as above
'crawl in opening'