Yosemite Falls is the highest measured waterfall in North America. Located in Yosemite National Park in the Sierra Nevada of California, it is a major attraction in the park, especially in late spring when the water flow is at its peak.

The total 2,425 feet (739 m) from the top of the upper falls to the base of the lower falls qualifies Yosemite Falls as the sixth highest waterfall in the world, though with the recent discovery of Gocta Cataracts, it appears on some lists as seventh. Although often referred to as a "two-stage drop", the falls actually consist of three sections:

Upper Falls: The 1,430-foot (440 m) plunge alone is among the twenty highest waterfalls in the world. Trails from the valley floor and down from other park areas outside the valley lead to both the top and base of Upper Yosemite Falls. The upper fall is formed by the swift waters of Yosemite Creek, which, after meandering through Eagle Creek Meadow, hurl themselves over the edge of a hanging valley in a spectacular and deafening show of force.

Middle Cascades: Between the two obvious main plunges there are a series of five smaller plunges collectively referred to as the Middle Cascades. Taken together these account for a total drop of 675 feet (206 m), more than twice the height of the Lower Falls. Because of the narrow, constricted shape of the gorge in which these drops occur and the lack of public access, they are rarely noted. Most viewpoints in the valley miss them entirely. Several vantage points for the cascades are found along the Yosemite Falls trail. Several hikers climbing down from the trail towards the cascades have required an expensive helicopter rescue due to steep and slippery terrain and features.

Lower Falls: The final 320-foot (98 m) drop adjacent to an accessible viewing area, provides the most-used viewing point for the waterfalls. Yosemite Creek emerges from the base of the Lower Falls and flows into the Merced River nearby. Like many areas of Yosemite the plunge pool at the base of the Lower Falls is surrounded by dangerous jumbles of talus made even more treacherous by the high humidity and resulting slippery surfaces
http://en.wikipedia.org/wiki/Yosemite_Falls