You hike into a canyon and do several rappels on your way back. I did it with my then 12 YO son in Water Canyon ten years ago. It’s about 30 minutes south of Zion, near to Hildale, former home of Warren Jeffs. We hiked over two miles, and completed 5 rappels on the way back, ranging from 50-90 feet.
I'd say you probably want to be young, in shape and experienced to be doing this. Sounds like an accident, it can happen when you are doing dangerous stuff.