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).

This undated handout photograph released by Taipei City Zoo on July 17, 2013 shows recently born panda cub of giant panda Yuan Yuan in an incubator at Taipei Zoo in Taipei. (Photo by AFP Photo/Taipei City Zoo)

This picture taken on September 9, 2014 shows a waiteress handing over food to customers at a prison themed restaurant in Tianjin. As more themed restaurants are popular in China, a “prison style” restaurent in Tianjin is aimed at reminding people to observe the law and to be good citizens. (Photo by Wang Zhao/AFP Photo)

People with red hair from all over the world gather on “Roodharigendag” (Redhead Day) in Breda, The Netherlands, 07 September 2014. The Redhead Day is celebrated annually at the old Dutch city on the first weekend in September. It offers cultural events, music, a picnic, a fashion show and art exhibitions from and for the red haired community. (Photo by Arie Kievit/EPA)

A squid in the Red Sea. Underwater photographer Andrey Nekrasov, 42, photographed bigfin reef squid in the pitch black Red Sea putting on an extraordinary light show when the sun goes down. (Photo by Andrey Nekrasov/Medavia/ABACAPress)

Whether they are the hunter or the hunted, these camouflage animals show natures incredible ability to blend in with its surroundings. Pictured perfectly concealed against their natural environment, the stunning pictures show the amazing lengths some animals will go to to stay out of sight. Here: The camouflage mappet moth looks like a fall lead in Switzerland. (Photo by Thomas Marent/Caters News/Ardea)

The British rock and roll group the Beatles talk to Ed Sullivan at CBS Studio 50 before their live television appearance on “The Ed Sullivan Show” in New York, February 10, 1964. From left to right are, Sullivan, John Lennon, Ringo Starr, holding a cigarette, and Paul McCartney. (Photo by AP Photo)

A newborn baby giraffe shows its tongue at the Planckendael zoo in Mechelen, 25 kilometers North of Brussels, Tuesday, February 18, 2014. The calf was born on Valentines day, February 14, and has a heart shaped spot on the hip. (Photo by Yves Logghe/AP Photo)