http://www.youtube.com/watch?v=DIym3B87SdI&feature=related (and this is just the kids)

Badwater Ultramarathon describes itself as “the world’s toughest foot race”. It is a 135 mile (215 km) course starting at 282 feet (85 m) below sea level in the Badwater Basin, in California’s Death Valley, and ending at an elevation of 8360 feet (2548 m) at Whitney Portal, the trailhead to Mount Whitney. It usually happens in July, when the weather conditions are most extreme and temperatures over 120 F (49 C) in the shade are not uncommon. Consequently, not many people?even among ultramarathoners?are capable of finishing this race.

The Course

Originally, the run was conceived as being between the lowest and the highest points in the contiguous United States: Badwater, Death Valley (-282 ft) and Mt. Whitney’s summit (14,496 ft). The two are only eighty miles apart on the map, but the land route between the two points is substantially longer, 146 miles, because of detours around lakebeds and over mountain ranges. Additionally, since the finish-line is 11 miles from the nearest trailhead, anyone who competes over the 146 mile race-distance must be capable of a total physical effort of 157 miles. Due to the two mountain ranges that must be crossed between Badwater and Whitney, the course’s cumulative elevation gain exceeds 19,000 feet (5,800 m).

In later years, as the United States Forest Service required summit permits to climb Mt. Whitney, the official course was shortened to end at Whitney Portal. The Badwater-to-Portal course is 135 miles long, with 13,000 feet (4,000 m) of cumulative elevation gain. Forest Service regulations do not allow competitive events in the John Muir Wilderness, however, many runners choose to continue tradition and complete the ascent to Mount Whitney’s summit on their own.

http://en.wikipedia.org/wiki/Badwater_Ultramarathon – “So far there have been no fatalities.”