I was always under the impression that the boulder rooms entrance was on the south end of the Boulder field along Charons garden trail, below and south of Apple and pear. I mean afterall the green hiking trail guide that you get at the refuge indicates that, and there ARE boulder rooms there complete with Bats.
On top of Elk Mountain, somewhere south of Apple pear in a canyon, I've also run into some chains that are attached to a wall above a narrow ledge where down below this ledge is a dark hole or cave that I can't see the bottom of to see how deep it is. There seems to be rooms in that area also.
To sum it up, the Refuge hiking brochures show the boulder rooms to be on or run along Charons garden trails.We entered these rooms by hiking north from Treasure lake until we reached the south end of the boulder field along Charons garden trail.
Is there more than one Boulder rooms?

More info on those chains would be appreciated also. What are they there for, who put them there, what for, how long have they been there, are they safe? I was afraid to use them with my 200 pounds plus. No idea how far it is to the bottom of that black pit below those chains.