The Grand Canyon Skywalk is a transparent horseshoe-shaped cantilever bridge and tourist attraction in Arizona near the Colorado River on the edge of a side canyon in the Grand Canyon West area of the main canyon. USGS topographic maps show the elevation at the Skywalk's location as 4,770 ft (1,450 m) and the elevation of the Colorado River in the base of the canyon as 1,160 ft (350 m), and they show that the height of the precisely vertical drop directly under the skywalk is between 500 ft (150 m) and 800 ft (240 m).

Patarawan fixes her boots as her parrot, Sim sits on her head as she goes shopping for dinner at a busy flooded market near the Chao Phraya river October 27, 2011 in Bangkok, Thailand. Hundreds of factories closed in the central Thai province of Ayutthaya and Nonthaburi as the flood waters began to reach Bangkok. Around 350 people have died in flood-related incidents since late July according to the Department of Disaster Prevention and Mitigation, with Thailand experiencing the worst flooding in 50 years. (Photo by Paula Bronstein/Getty Images)

A gaggle of goslings huddle together under the protective wing of a parent along the bank of the Deschutes River as a heavy downpour passes through Bend, Oregon, late Wednesday, April, 20, 2106 afternoon. (Photo by Ryan Brennecke/The Bulletin via AP Photo)

Evel Knievel is shown in his rocket before his failed attempt at a highly promoted 3/4-mile leap across Snake River Canyon in Twin Falls, Idaho, on September 8, 1974. The jump failed when the parachute on his rocket malfunctioned, opening prematurely. Knievel was uninjured. (Photo by AP Photo)

The sun streaks through the fall foliage at sunrise along the Potomac River in Arlington, Va., Wednesday, November 4, 2015 on a warm fall day in the nation's Capitol area. (Photo by J. David Ake/AP Photo)

Members of the “Avalon” team wearing 14th century knight costumes fight against each other on the bank of the Yenisei River during the regional amateurs tournament of clubs of historical reconstruction, “The Battle of the Nations 2015. Siberia”, in Krasnoyarsk January 24, 2015. (Photo by Ilya Naymushin/Reuters)

Vietnam’s Son Doong cave, the largest in the world, could hold a 40-story skyscraper inside. The pristine ecosystem has its own river and jungle. Despite its size, Son Doong wasn’t discovered until 1991. It was lost again for nearly two decades and was fully explored for the first time in 2009. (Photo by Jason Speth/HuffPost)

A young girl sells balloons by the Yamuna River as devotees carrying idols of the Hindu god Ganesh, the deity of prosperity, immerse the idol on the last day of the ten-day-long Ganesh Chaturthi festival in Delhi, India, September 15, 2016. (Photo by Cathal McNaughton/Reuters)