The holder of half a dozen world records will walk across the Grand Canyon on a steel cable with nothing but the Little Colorado River 1,500 feet below on June 23. With no tethers or safety nets, the walk will be the highest tightrope attempt ever for the 34-year-old, at a height taller than the Empire State Building. Last year, Wallenda, a seventh-generation member of the “Flying Wallendas” family of acrobats, became the only person to walk a wire over the brink of Niagara Falls. Photo: Nik Wallenda walks across a tightrope 200 feet above U.S. 41 on January 29, 2013 in Sarasota, Florida. (Photo by Tim Boyles)

A Geoffroy's Monk Saki is seen at the Parque de Las Leyendas zoo in Lima, Peru, February 14, 2018. (Photo by Guadalupe Pardo/Reuters)

A hot air balloon in tortoise shape flies in the air during the Tazaungdaing air balloon festival in Pyin Oo Lwin, Myanmar, 25 November 2015. During the festival, hot air balloons made of multicolored papers and hung with paper lanterns, fireworks and fire sticks are exploded in mid-air. (Photo by Hein Htet/EPA)

A rider rears up on his horse while surrounded by a cheering crowd during the traditional Fiesta of Sant Joan (Saint John) in downtown Ciutadella, on the island of Menorca, Spain June 23, 2016. Horse riders are representatives of ancient Ciutadella society – nobility, clergy, craftsmen and farmers. (Photo by Enrique Calvo/Reuters)

A model poses at Checkpoint Charlie, a historic place in the German capital to promote the fashion magazine “Sous” on June 12, 2012. (Photo by Maurizio Gambarini)

Wildlife agency rangers rescue a Malayan tapir, an endangered species on the International Union for Conservation of Nature (IUCN) Red List, after it fell into a villager's fish pond in Pekanbaru, Riau on April 20, 2021. (Photo by Wahyudi/AFP Photo)

People walk past the Sleepwalker, a sculpture along the High Line in New York, US on May 10, 2016. The hyperrealistic work by Brooklyn artist Tony Matelli is part of the linear park’s Wanderlust exhibition. (Photo by Xinhua/Barcroft Images)

A wild cow jumps over revelers in the bullring after the first running of the bulls at the San Fermin festival in Pamplona, northern Spain, July 7, 2016. (Photo by Eloy Alonso/Reuters)