Most pet cats will become timid or defensive when outdoors, but not Millie – after being adopted by her mountain-climbing owner Craig Armstrong, Millie has become a feline hiking and mountain-climbing legend.

In this May 24, 2016 photo, a young boy descends the Qullqip'unqu mountain looking out at the tens of thousands of pilgrims gathered to celebrate the three-day festival Qoyllur Rit’i, translated from the Quechua language as Snow Star, in the Andean Sinakara Valley, in Peru's Cusco region. The celebration that mixes Catholic and indigenous beliefs honors Jesus as well as the area’s glacier, which is considered sacred among some indigenous people. While the native celebration is far older, the Christian part of the ritual stretches back to the 1700s, when Jesus is said to have appeared to a young shepherd in the form of another boy. (Photo by Rodrigo Abd/AP Photo)

The sun rises between Sgurr nan Gillean and Knight’s Peak, Black Cuillin, Isle of Skye. (Photo by Adrian Trendall/Mountain Photo of the Year)

Kurt Arrigo is Malta’s most eminent and one of the world’s finest marine photographers. ­­His illustrious and diverse career has seen him capture dramatic action at elite international sporting events.

Deadwood is pictured in the onetime spa and resort town Epecuen, November 5, 2015. Over the past few years the town of Epecuen, located 550 km (341 miles) southwest of Buenos Aires, has been attracting tourists with its eerie apocalyptic atmosphere after a flood submerged it in salt water for more than two decades. Photo by Enrique Marcarian/Reuters)

Rescued Dutch hikers exit a search and rescue snowcat after they were brought safely to Grotli, Norway, February 26, 2016. Thirteen Dutchmen who were stranded while hiking in central Norway's mountains were found after snowmobile patrols by the Red Cross. Snowcats from the Red Cross are now moving ahead to pick the hikers up. (Photo by Torstein Boe/Reuters/NTB Scanpix)

Twiggy the Water-Skiing Squirrel is an animal novelty act, featuring a squirrel who skis around a heated pool. The act began in 1979 by Chuck and Lou Ann Best and started with an appearance on Real People. It has been featured on numerous television shows, newspaper articles, and websites.