The Red Castle Lake to Trailhead section of the Whitewater River in Wyoming is a popular destination for whitewater enthusiasts. The ideal streamflow range for this section is between 150 and 500 cubic feet per second (cfs), with flows above 500 cfs considered dangerous. The class rating for this section is class III, with several class IV rapids along the way. The segment mileage for this run is approximately 12 miles.

One of the most notable rapids in this section is known as "The Narrows," which is a class IV rapid that requires advanced skills to navigate. Other challenging rapids include "Big Drop" and "Slide" rapids. The river also features beautiful scenery, with views of the stunning Red Castle Mountain and surrounding wilderness.

Regulations for this area include a permit system for overnight camping, as the run passes through the Uinta-Wasatch-Cache National Forest. Visitors are required to pack out all trash and waste and are encouraged to practice Leave No Trace principles.

Overall, the Red Castle Lake to Trailhead section of the Whitewater River offers a thrilling and scenic adventure for experienced whitewater paddlers within a pristine wilderness setting.