Muslims pray at the top of Mount Al-Noor during their Umrah Mawlid al-Nabawi “Birthday of Prophet Mohammad” in the holy city of Mecca, Saudi Arabia January 16, 2016. Muslims believe Prophet Mohammad received the first words of the Koran through Gabriel, at the top of Mount Al-Noor in the holy city of Mecca. (Photo by Amr Abdallah Dalsh/Reuters)

The adventurous explorers have snapped themselves in shark-infested waters, at the side of an active volcano, atop a Hong Kong skyscraper surrounded by toxic smog, and even perched on the top of iconic Rio statue of Christ the Redeemer. Here: Ervin Punkar using a selfie stick to take a photo from the very top of the 600ft TV tower in Tartu, Estonia. (Photo by Ervin Punkar/Caters News Agency)

A woman aims a World War II machine gun at a military show during celebration of the Defenders of the Fatherland Day in St.Petersburg, Russia, Tuesday, February 23, 2016. The day, celebrated in Russia on February 23, honors the nation's military and is a nationwide holiday. (Photo by Dmitri Lovetsky/AP Photo)

An ethnic Armenian fighter carries Kalashnikov machine guns to his comrade-in-arms at Martakert province in the separatist region of Nagorno-Karabakh, Azerbaijan, Monday, April 4, 2016. (Photo by Vahan Stepanyan/PAN Photo via AP Photo)

A 2S5 Giatsint self- propelled gun fires during tactical exercises held by artillery detachments of the Russian Eastern Military District' s 5th Army at the Sergeyevsky training ground in Primorye Territory, Russia on March 21, 2017. Over 2500 servicemen practice combat skills received in 2017 winter training exercises. (Photo by Yuri Smityuk/TASS)

A Thai and foreign revelers battle with water guns during the annual Songkran celebration at Khaosan Road, a tourist spot in Bangkok, Thailand, 12 April 2017. The four southeast Asian nations of Myanmar, Thailand, Cambodia and Laos started the Buddhist new year, known as Thingyan in Myanmar and Songkran in Thailand, on April 13. (Photo by Rungroj Yongrit/EPA)

An undated archive picture shows a dog pulling a Belgian machine gun at an unknown location in northern France. A Viscount in the Armoured Cavalry Branch of the French Army left behind a collection of hundreds of glass plates taken during World War One (WWI) that have never before been published. The images, by an unknown photographer, show the daily life of soldiers in the trenches, destruction of towns and military leaders. The year 2014 marks the 100th anniversary of the start of WWI. (Photo by Collection Odette Carrez/Reuters)

U.S. soldiers from 145th Field Artillery Battalion deployed from the United States fire Paladin self propelled gun during the Foal Eagle training exercise at firing point 180 at the Rodriguez Live Fire Range on March 15, 2012 in Pocheon, South Korea. (Photo by Chung Sung-Jun/Getty Images)