The McKenzie River's second section, known as McKenzie River Seg B, is a popular spot for whitewater rafting in Oregon. The ideal streamflow range for this section is between 1,200 and 2,500 cfs, with peak season being in late spring and early summer. The class rating for this section is class III-IV, making it a moderate to difficult level of rapids.

The segment mileage for McKenzie River Seg B is approximately 12.5 miles, starting at Belknap Bridge and ending at Paradise Campground. Along this section, there are several notable rapids and obstacles, including Boxcar, Marten Rapids, and Horseshoe Falls. Boxcar is a class IV rapid with a steep drop and technical maneuvering required to navigate through it. Marten Rapids is a class III rapid with several large waves, and Horseshoe Falls is a class III+ rapid with a sharp turn and a large boulder in the middle.

There are specific regulations to this area, including a permit system for commercial outfitters and a no-alcohol policy on the river. Additionally, all rafters must wear a personal flotation device while on the river.