Authorities said the call for help came in around 2:10 p.m. The child was on a hike with family members.
At some point, he and another family member were near the top of a 25-foot waterfall when they fell down into the pool of water below.
Witnesses at the scene said the child was underwater for a short time before being pulled out, and they called 911. A San Bernardino County sheriff's air rescue team headed to the location and conducted a hoist rescue.
The child was breathing and taken to a nearby trauma center for an evaluation. Hospital staff determined the child had suffered no injuries in the fall.