The map we bought at the Wichita Mountains National Wildlife Refuge, OK visitor center shows a trail (from Sunset to Treasure Lake) that's only partly there. It's covered, for about 1/4 mile, by an impressive boulder field on the western side of Elk Mountain. The field makes for some fun scrambling. And, it's easy to find this big room down near the bottom of the rock field (southern end). That's Ronn, me and my son Curtis in the image. I've uploaded a separate image with an annotated map that can help you locate the boulder field.