Blue Hole of Santa Rosa

An artesian spring sinkhole on Route 66 in Santa Rosa and the most famous dive site in the US Mountain West. The bell-shaped pool is about 60 feet across at the surface, widening to roughly 130 feet at the 81-foot bottom, with a constant 61 F temperature and visibility around 100 feet thanks to a flow that renews the water continuously. A city-issued dive permit is mandatory, purchased at the on-site dive center, and the high altitude (~4,600 ft, with higher passes on the drive out) demands altitude dive planning.