Geumganggul is a limestone cave set in the rock face above the Seorakdong valley, reached by a trail that branches off the main valley route and climbs steeply via metal steps and ladders. The cave itself is relatively small but contains a simple Buddhist shrine, and the cave mouth offers a framed view back down the valley. The ascent takes about 30 minutes from the junction and involves some exposed ladder sections.
The trail to Geumganggul is often combined with the Ulsanbawi hike on the same day, as the trails overlap for part of their routes. The cave rewards the effort with solitude — most visitors on the main Cheonbuldong valley route pass the junction without diverting. The cave is one of several sacred rock sites in Seoraksan used for centuries by Buddhist monks seeking isolated meditation spots.