A muslim pilgrim walks through the site where dead bodies are gathered in Mina, Saudi Arabia during the annual hajj pilgrimage on Thursday, September 24, 2015. Hundreds were killed and injured, Saudi authorities said. The crush happened in Mina, a large valley about five kilometers (three miles) from the holy city of Mecca that has been the site of hajj stampedes in years past. (Photo by AP Photo)

Hikers walk to reach the top of Naqba Rum area in South Sinai, Egypt, November 20, 2015. Bedouins in the "Sinai is Safe" group guided more than 100 hikers over a 25 km (15 mile) trek over the trails of the White Canyon and the Closed Canyon. The NGO aims to challenge mainstream perceptions of the area by encouraging Nile Valley residents to explore the untamed wilderness with the Bedouin tribes. (Photo by Asmaa Waguih/Reuters)

An old locomotive train that was used for transporting coal is preserved as a monument at Ny-Alesund, in Svalbard, Norway, October 11, 2015. A Norwegian chain of islands just 1,200 km (750 miles) from the North Pole is trying to promote new technologies, tourism and scientific research in a shift from high-polluting coal mining that has been a backbone of the remote economy for decades. (Photo by Anna Filipova/Reuters)

In this photo taken October 16, 2012 and provided by Oracle Team USA, crew members of the capsized Oracle Team USA AC72 boat are rescued after being swept past the Golden Gate Bridge in San Francisco. The America's Cup champion syndicate is assessing the damage to its 72-foot catamaran, after it capsized and was swept by a strong current more than four miles past the Golden Gate Bridge before rescue boats could control it. (Photo by Guilain Grenier/Oracle Team USA/Associated Press)

Centenarian Sikh runner Fauja Singh poses for pictures after being the first person to officially enter for next year's Edinburgh Marathon on September 1, 2011 in Edinburgh, Scotland. A world record holder, aged 100, Fajua Singh has run seven marathons, all after his 89th birthday. He officially opened the entry process by signing up for his last ever 26 mile event in Edinburgh. (Photo by Jeff J Mitchell/Getty Images)

A Chinese tourist wears protective gloves as she holds a baby Siberian tiger as they pose for pictures at the Heilongjiang Siberian Tiger Park on August 16, 2017 in Harbin, northern China. The center is one of two Siberian tiger parks in the Chinese province of Heilongjiang, about 500 kilometers (300 miles) from the border with Russia. It is considered the world's largest for breeding the Siberian, or Amur, tiger which is listed as endangered by the World Wildlife Federation. (Photo by Kevin Frayer/Getty Images)

Buildings in Nogales, Mexico (R) are separated by a border fence from Nogales, Arizona, United Sates, October 9, 2016. Building a wall along the U.S.- Mexico border has been a contentious subject in this year's U.S. presidential election. In parts of California and Arizona, a wall already exists. It runs across rocky deserts, flowing sand dunes and miles of agricultural land. (Photo by Mike Blake/Reuters)

Lava cascades down the slopes of Mayon volcano as seen from Legazpi city, Albay province, around 340 kilometers (210 miles) southeast of Manila, Philippines, Monday, January 15, 2018. More than 9,000 people have evacuated the area around the Philippines' most active volcano as lava flowed down its crater Monday in a gentle eruption that scientists warned could turn explosive. (Photo by Earl Recamunda/AP Photo)