Located just a mile west of the charming town of Grace, Black Canyon of the Bear is a striking river gorge of 100-ft high black lava cliffs. The water once ran deep here, almost to the top of the cliffs, but the construction of Grace Dam means it is low most of the year round. This spectacular canyon is renowned as one of the most challenging kayak sites in the whole of the country (Class IV and V) and there is a Whitewater Festival held here in April.
If you go:
Other natural attractions near Grace include ice caves, natural springs and the world's only 'captive' (i.e. valve-controlled) geyser, in nearby Soda Springs, which is allowed to erupt on the hour, every hour.
Links:

Turner Road
Grace, Idaho 83241 USA
Mailing address:
Pioneer Country Travel Council
PO Box 669
Lava Hot Springs, ID 83246 USA
Phone Numbers:
Pioneer Country Travel Council
+1 (208) 776-5221
+1 (208) 776-5221
Toll-free
+1 (888) 201-1063
+1 (888) 201-1063