The Whitewater River run in Hawaii begins where pipes first meet the river and the main diversion begins to the mouth at the Pacific Ocean. The ideal streamflow range for this run is between 200-400 cfs. The river is rated as a Class III-IV, which means it has moderate to advanced rapids and requires experienced paddlers. The segment mileage for this run is approximately 7 miles.

The river rapids and obstacles include tight chutes, big drops, and steep boulder gardens. The most challenging rapids on this run are the "Hole-in-the-Rock" and "Elevator Shaft." Paddlers should be aware of the strong eddies and currents that can make navigating the rapids more difficult.

There are specific regulations that apply to this area. Paddlers must obtain a permit to access the Whitewater River run, and the number of permits issued per day is limited to protect the environment and ensure the safety of paddlers. Additionally, all paddlers are required to wear a personal flotation device and a helmet while on the river.

In conclusion, the Whitewater River run in Hawaii is a challenging and thrilling experience for experienced paddlers. With its ideal streamflow range, Class III-IV rating, and specific rapids and obstacles, it provides a unique adventure for those seeking an adrenaline rush. However, paddlers must also be aware of the specific regulations in place to protect the environment and ensure their safety.