Just south of the Hoover Dam on the Nevada side of the canyon is the Sauna Cave. This cave was drilled by miners working on Hoover Dam while it was being constructed. It is a deep cave with calcium carbonate crystals on the walls.[2] At the end of the cave is a hot spring, which causes temperatures in the cave to reach 120 °F (49 °C).[citation needed]
One prominent canyon that splits from this canyon south of the Hoover Dam is Boy Scout Canyon. Boy Scout Canyon has water running through it that is warmed from a geothermal source.[2]
On the Arizona side of the river, there are several large hot springs that can be found by taking a trail north from a larger bay about 4 to 5 miles (6.4 to 8.0 km) south of the Hoover Dam.[3]
The Colorado River traveling through the Black Canyon is designated as the Black Canyon Water Trail, a National Water Trail.