The Fractions River Run on the Arkansas River in Colorado is a Class III section of water that is best floated from May to August. The water level can range from 700-1300 CFS, with the best flow being around 1000 CFS. This run includes several challenging rapids, including Frog Rock, Tombstone, and Zoom Flume. The most significant obstacle is the Narrows, a narrow chute with large boulders that require precise navigation. Overall, the Fractions River Run is a thrilling adventure for intermediate and experienced paddlers looking for a challenging whitewater experience.