Northgate Canyon River Run in Colorado is a thrilling Class III and IV river run that is best tackled in the late spring and early summer, when water levels are at their highest. The rapids are intense, with steep drops, tight chutes, and large waves that will keep experienced paddlers on their toes. Specific river obstacles include the "Four Mile" rapid, which features a large hole that can easily flip boats, and the "Sledgehammer" rapid, which requires precision steering to avoid large rocks. With a recommended flow of 800-1200 CFS, this river run is not for beginners, but offers a thrilling experience for those looking for a challenge.