Lower Black Box of the San Rafael Trail Professional Review and Guide
"The Lower Black Box is a deep, narrow canyon of the San Rafael River located on the eastern edge of the San Rafael Swell. This hike involves floating 3.7 miles down the river through the Lower Black Box, and then walking back 2.6 miles along the eastern side of the gorge to the starting point. The trip is an exciting one with a lot to see, but it requires careful planning and it isn’t suitable for everyone. First, the trip through the Lower Black Box shouldn’t be attempted by anyone who doesn’t know how to swim. It is also important that everyone in the group have an inflated inner tube to float through the long, deep pools.
You should include a 30-foot length of rope in your pack for emergency use and for lowering down backpacks. As for clothing, shorts, a shirt, and wettable boots are best. You will be walking over submerged rocks much of the time, so be sure you have good footwear. Also, forget about trying to keep your things dry. Everything you take with you will be soaking wet when you finish with this trip. Once you enter the Black Box it is difficult to turn around. It isn’t the sort of place you want to get caught in after dark, so be sure to allow plenty of time for the trip."