Two attendees compete in the biggest vape cloud competition at the Vape Summit 3 in Las Vegas, Nevada May 2, 2015. According to new research provided to Reuters, youngsters say that performing tricks is one of the top two reasons they began using e-cigs. (Photo by David Becker/Reuters)

These adrenaline-junkie climbers go to extraordinary lengths, and heights, to take a selfie. Hundreds of metres above the ground, the climbers risk their life and liberty as they scale huge structures and photograph the results. Known as urban exploration, the aim is to find extremely high and almost inaccessible city buildings and reach their dizzying summits. (Photo by Yaroslav Segeda/Solent News)

Auto worker Christopher Brower screws a component into the cab of a four-door F150 at Ford's Kansas City Assembly Plant where new aluminum intensive Ford F-Series pickups are built in Claycomo, Missouri May 5, 2015. (Photo by Dave Kaup/Reuters)

Figurines representing French Brigade of Lancers are seen on a 40-square-metre miniature model of the June 18, 1815 Waterloo battlefield, in Diest, Belgium, in this picture taken on April 29, 2015. Waterloo enthusiast Willy Smout said he spent 40,000 hours and around 150,000 euros over the past 40 years, to recreate the battlefield as closely as possible in a purpose-built room in his house. (Photo by Francois Lenoir/Reuters)

The Virgin of El Rocio is carried by pilgrims during a procession around the shrine of El Rocio in Almonte, southern Spain, May 25, 2015. Every spring hundreds of thousands of devotees converge at a shrine to pay homage to the Virgin del Rocio during an annual pilgrimage which combines religious fervour and festive colour. (Photo by Marcelo del Pozo/Reuters)

A farmer tends to his field as Mount Sinabung releases pyroclastic flows in Tiga Pancur, North Sumatra, Indonesia, Saturday, June 13, 2015. The volcano, which was put on it highest alert level last week, has sporadically erupted since 2010 after being dormant for 400 years. (AP Photo/Binsar Bakkara)

An actress performs in a puppet theater show at an UNRWA school in Burj al-Barajneh in Beirut May 14, 2015. The Arab Puppet Theatre Foundation (APTF) is touring the 68 schools of the UN refugee agency's UNRWA and performs for all 39,000 Palestinian students in Lebanon, in a project with UNICEF and UNRWA. (Photo by Mohamed Azakir/Reuters)

A Western Lowland Gorilla baby named “Mjukuu”, that was born in October last year, rides on the back of its Mother “Mbeli” in their enclosure at Taronga Zoo in Sydney, Australia, May 19, 2015. The baby gorilla was born six days ago, and is the second sired by the zoo's new Silverback, Kibali, who arrived from France in 2012. (Photo by David Gray/Reuters)