The Whitewater River Run from the headwaters to the southern boundary of Zion National Park in Utah is a stretch of river that is ideal for experienced kayakers and rafters. The ideal streamflow range for this stretch is between 200-400 cfs, with higher flows creating more challenging rapids. This section of the river is rated as Class III-IV, with some sections reaching Class V during high flow events. The segment mileage for this run is approximately 16 miles.

There are several notable rapids and obstacles along this stretch of the river, including the technical Staircase rapid, the steep and fast Serpentine Falls, and the infamous Black Hole rapid, which is a Class V rapid that should only be attempted by expert kayakers and rafters. There are also several rocky sections and tight channels that require precise navigation.

There are specific regulations in place for this area, including a permit system for commercial river outfitters and a limit on the number of daily permits issued. Additionally, all visitors are required to adhere to Leave No Trace principles and pack out all trash and waste. Swimming is not recommended due to the fast-moving water and numerous obstacles.

Overall, the Whitewater River Run from the headwaters to the southern boundary of Zion National Park offers a thrilling and challenging experience for experienced kayakers and rafters, but should only be attempted with caution and respect for the natural environment.