A woman looks at La Paz city from the Jacha Qhatu cable car station in El Alto, July 23, 2015. Bolivia already has the largest urban cable car system in the world. Now the booming country is tripling the size of the network and will soon have nine lines whizzing above the administrative capital of La Paz. (Photo by David Mercado/Reuters)

Lisa Yu crawls through a mud pit under low slung barbed wire as she competes in The Tough Bloke Challenge on March 4, 2012 in Melbourne, Australia. The Tough Bloke Challenge is one of the most gruelling adventure runs in Australia consisting of 18 obstacles over a 6 km cross-country course laden with thick mud-pits and ice-cold water crossings. (Photo by Scott Barbour/Getty Images)

Two women jump into a frozen pond as they compete in the Polar Plunge at Frozen Dead Guy Days in Nederland, Colorado March 14, 2015. The winter festival in the small mountain town commemorates the 1994 discovery of the corpse of Bredo Morstol, which is now housed in a shed on dry ice above the town. (Photo by Rick Wilking/Reuters)

Zahra Lari runs in a scene shot for the Nike Middle East ad campaign filmed in Dubai, UAE, February 10, 2017. An online commercial released by Nike (NKE.N) this week that showed Arab women fencing, boxing and spinning on ice-skates has stirred controversy over its attempt to smash stereotypes about women leading home-bound lives in the conservative region. (Photo by Reuters/Nike)

This November 8, 2019, photo provided by John Guillote shows a view from the main lab of the Sikuliaq in the Chukchi Sea. University of Washington scientists onboard the research vessel are studying the changes and how less sea ice will affect coastlines, which already are vulnerable to erosion because increased waves delivered by storms. More erosion would increase the chance of winter flooding in villages and danger to hunters in small boats. (Photo by John Guillote via AP Photo)

Beryl Lipton, left, douses Matt Lee during the ice bucket challenge at Boston's Copley Square, Thursday, August 7, 2014 to raise funds and awareness for ALS. The idea is: pay up for charity or get doused. The fund-raising phenomenon is catching on fast, propelled by popular videos of the dunkers and the dunked – including famous athletes and entertainers – posted on social media sites. And the challenges are raising tens of thousands of dollars and immeasurable awareness for causes from ALS to breast cancer to a camp for kids who've lost a father to war. (Photo by Elise Amendola/AP Photo)