The Green River in North Carolina is perhaps best known as one of the extreme whitewater kayaking challenges in North America that is run on a regular basis. The "Narrows" section features an overall drop of over 100 feet per mile (19 m/km) with one section dropping at a horrendous rate of 350 feet per mile (66 m/km). Normally there would not be enough water to paddle the "Narrows" section most of the year, but controlled dam releases upstream make it possible to run it on a fairly regular basis.