Radium Hot Springs is a wild, primitive soak perched above the Colorado River in the rugged canyon country between Kremmling and State Bridge, Colorado — on BLM land in the heart of the popular Radium Recreation Area. With a rock-rimmed pool built against a sheer cliff and the Colorado rushing below, it's one of the most scenic and adventurous riverside soaks in the state.

The pool itself is a simple, sandy-bottomed soaking spot roughly 10 by 18 feet, fed by a hot spring (around 97 degrees at the source) that mixes with cool river water for a comfortable soak. Reaching it is part of the fun — and the challenge: from the parking area it's a short but steep hike, with the final descent to the pool requiring a careful down-climb of a roughly 50-foot rock chimney using natural foot- and handholds. Many visitors actually arrive the easy way, by raft or kayak floating the Colorado.

A serious safety note: Radium is also a famous cliff-jumping spot, but leaping from the canyon walls into the river is genuinely dangerous and has caused serious injuries — submerged rocks and shallow, fast water mean the posted “jump at your own risk” warning should be taken to heart. The chimney down-climb to the pool also demands caution and isn't for everyone or for small children.

The best time is summer through early fall, after spring runoff drops — from roughly March into late May the pool can be flooded, cold, or washed out entirely. There's camping at the parking area and nearby BLM sites (day-use and camping fees apply April through November). Bring water, sturdy shoes, and good judgment, pack out everything, and Radium rewards you with a one-of-a-kind Colorado River soak.