Gore Canyon is a short, steep, isolated gorge on the upper Colorado River in southwestern Grand County, Colorado, where the river cuts past the northern end of the Gore Range and marks the southwestern end of Middle Park. About three miles long, it is largely roadless and is reached mainly by whitewater boats and the Union Pacific Railroad, whose construction through the gorge was a major engineering feat. The canyon is famous for extremely difficult class V whitewater, first rafted in the 1970s and now central to American whitewater culture through expert runs and an annual festival. It also provides habitat for pronghorn, bald eagles, trout, and reintroduced bighorn sheep.