Question: How long does is take to complete the Grand Canyon Ultra Marathon?
About the article "Grand Canyon", section "Activities".

Candidate passages:
Other desert marathons include the world famous Marathon Des Sables or MdS, a race through the Sahara desert over six days, covering more than five marathons.
Marathon Des Sables.
A new 126 km ultra marathon is following the Namibian Ultra Marathon format and is launching in 2011, Grand Canyon 24h Ultra. 
The Grand Canyon 24 hour Ultra Marathon is a 24 hour ultramarathon that takes the participants through one of the most striking environments on earth, the Grand Canyon.
The race took place for the first time in October, 2010.
The race takes participants out on the North Rim of the Grand Canyon, the much less visited area of the Canyon.
The race is a race in 24 hours, similar to the Namibian ultra marathon.
The runners are self reliant during the race and have to carry all food and water with them.
There are water stations during the route where water can be filled up.
The distance is the same as three standard marathons.  
The Antarctic Ice Marathon was established by Richard Donovan / Polar Running Adventures to enable marathon runners to complete a marathon on all seven continents.
It also enables athletes to complete the marathon grand slam - a marathon on all seven continents and the North Pole.
The seventh running of the Antarctic Ice Marathon and 100 km race took place at 80° south on 7 December 2011.
Participants are flown from Punta Arenas, Chile to the race location in the interior of the Antarctic and experience anything from subzero temperatures to 24 hours of daylight while there.
It is expected that on 20 November 2012, the eighth Antarctic Ice Marathon will take place at 80 degrees south, just a few hundred miles from the South Pole at the foot of the Ellsworth Mountains. 
Aside from casual sightseeing from the South Rim (averaging 7,000 feet [2,100 m] above sea level), rafting, hiking, running and helicopter tours are especially popular.
The Grand Canyon Ultra Marathon is a race over 24 hours.
The floor of the valley is accessible by foot, muleback, or by boat or raft from upriver.
Hiking down to the river and back up to the rim in one day is discouraged by park officials because of the distance, steep and rocky trails, change in elevation, and danger of heat exhaustion from the much higher temperatures at the bottom.
Rescues are required annually of unsuccessful rim-to-river-to-rim travelers.
Nevertheless, hundreds of fit and experienced hikers complete the trip every year.
Camping on the North and South Rims is generally restricted to established campgrounds and reservations are highly recommended, especially at the busier South Rim.
There is at large camping available along many parts of the North Rim managed by Kaibab National Forest.
North Rim campsites are only open seasonally due to road closures from weather and winter snowpack.
All overnight camping below the rim requires a backcountry permit from the Backcountry Office (BCO).
Each year Grand Canyon National Park receives approximately 30,000 requests for backcountry permits.
The park issues 13,000 permits, and close to 40,000 people camp overnight.
The earliest a permit application is accepted is the first of the month, four months before the proposed start month.
Tourists wishing for a more vertical perspective can board helicopters and small airplanes in Las Vegas, Phoenix and Grand Canyon National Park Airport (seven miles from the South Rim) for canyon flyovers.
Scenic flights are no longer allowed to fly within 1500 feet of the rim within the national park because of a late 1990s crash.
The last aerial video footage from below the rim was filmed in 1984.
However, some helicopter flights land on the Havasupai and Hualapai Indian Reservations within Grand Canyon (outside of the park boundaries).
Recently, the Hualapai Tribe opened the glass-bottomed Grand Canyon Skywalk on their property, Grand Canyon West.
The Skywalk has seen mixed reviews since the site is only accessible by driving down a dirt road, costs a minimum of $85 in total for reservation fees, a tour package and admission to the Skywalk itself and the fact that cameras or other personal equipment are not permitted on the Skywalk at any time due to the hazard of damaging the glass if dropped.
The Skywalk is about by road from Grand Canyon Village at the South Rim.
Pilar Geijo (born 19 September 1984 in Buenos Aires) is a Marathon swimmer from Argentina.
She has won most of the world's greatest ultra-marathon swimming competitions: the 2010 Traversée Internationale du Lac Memphrémagog (34K event), the 2011 Maratona del Golfo Capri Napoli Marathon (36K), the 2010 16K FINA Open Water Swimming Grand Prix in Sumidero Canyon in Mexico, and the longest race in the world, the 88K Hernandarias-Parana FINA Grand Prix event (88K) in Argentina.
She has won the FINA Grand Prix circuit in 2010 and 2011.