Free solo climbing is arguably the purest form of climbing but obviously also carries the highest risks. Free solo climbing (also known as free soloing) is a form of climbing whereby the climber (known as a free soloist) does not use any hardware such as ropes, harnesses or other gear during their ascent. For practical purposes, 20 feet off the ground is commonly considered free soloing. If a fall will almost certainly result in death, that is soloing. It is mostly practiced on routes that are familiar to the climber and where its difficulty lies well below the climber's abilities. However, inherent risks such as loose rocks or sudden change in weather are always present and fatalities are not unknown to the practice. Free soloing belongs to the group of extreme sports. One famous practitioner of the sport was Dan Osman who was killed in an unrelated activity, a "controlled free-fall" jump in Yosemite National Park. Yosemite climbing program manager and park ranger Mark Fincher said there has been only one confirmed death from free-soloing at the park, that of Derek Hersey, a high-profile free-soloer who died on Sentinel Rock in 1993. The challenge of free soloing is (or should be) mainly a mental game of staying focused on what the climber is doing. Doing the move isn't the game. Free soloing should usually not be hard in a physical sense.

Another well-known practitioner, Alain Robert ("spiderman"), has scaled dozens of skyscrapers around the world — a sport known as buildering — and several mountains, without using any safety equipment.

Free soloing on seacliffs, where a climber falling into deep water may avoid injury, is known as deep water soloing. Remaining close to the ground and using protective mats is known as bouldering and is another, safer alternative.

Some of the driving forces in rock climbing and free soloing from 1900 to today: Paul Preuss, Henry Barber, John Bachar, Dan Osman, Derek Hershey, Dean Potter.

Sources

• Edge of Oblivion - Free-solo rock climbers feel spiritual lure, Sheila Mulrooney Eldred. Fresno Bee, April 8, 2004 ^*
• Ament, Pat (2001)."A History of Free Climbing in America"

Footnotes