Inside the Afar Triangle in Ethiopia’s Danakil desert, camel caravans are used to carry salt. For centuries, the essential mineral has been mined by the Afar people, known for their ability to withstand extremes. The terrain is rugged, travelers are scarce and so are motor vehicles, where the average annual temperature is the highest in the world, and can rise to 122 degrees Fahrenheit, 50 degrees Celsius. (Photo by Ziv Koren/Polaris)

Revellers celebrate moments before the rocket fire or “Txupinazo” marks the start of the Festival of San Fermin (or Sanfermines) at Consistorio square in Pamplona, Spain, 06 July 2014. The annual nine day long running-with-the-bulls fiesta commemorates St. Fermin, Pamplona's patron saint. (Photo by Javier Lizin/EFE)

Ebiowei, 48, carries an empty oil container on his head to a place where it would be filled with refined fuel at an illegal refinery site near river Nun in Nigeria's oil state of Bayelsa November 27, 2012. Locals in the industry say workers can earn $50 to $60 a day. Thousands of people in Nigeria engage in a practice known locally as “oil bunkering” – hacking into pipelines to steal crude then refining it or selling it abroad. The practice, which leaves oil spewing from pipelines for miles around, managed to lift around a fifth of Nigeria's two million barrel a day production last year according to the finance ministry. (Photo by Akintunde Akinleye/Reuters)

Several beaches along South Florida's Atlantic coast line were closed after thousands of sharks were seen migrating in the waters. The sharks were migrating from Boca Raton to Jupiter since the beginning of March, marine biologists told NBC Miami. Photo: A spinner shark swims just offshore on Midtown Beach in Palm Beach on Tuesday. (Photo by Jeffrey Langlois/Palm Beach Daily News)

An Oakland Raiders cheerleader performs during the second half of an NFL football game against the Pittsburgh Steelers in Oakland, Calif., Sunday, October 27, 2013. (Photo by Marcio Jose Sanchez/AP Photo)

The #8 DP Starworks Motorsports Ford Rley driven by Enzo Potolicchio, Ryan Dalziel, Alex Popow, Lucas Luhr and Allan McNish runs off the track during the Rolex 24 at Daytona International Speedway on January 28, 2012 in Daytona Beach, Florida. (Photo by John Harrelson/Getty Images)

These black-and-white photos are taken from the new book “Armoured Warfare in the First World War 1916 – 1918” by Anthony Tucker-Jones and published by Pen & Sword Military. Here: British troops hitch a ride on a Mark IV after the massed tank fleet spearheading attack at Cambrai on November 20, 1917. (Photo by Anthony Tucker-Jones/Mediadrumworld.com)

Ma Jiaqi, 5, and her mother arrive at Beijing Railway Station for their train to Changchun of Jilin province, in Beijing, China, January 25, 2016. According to traffic police, over 2.9 billion trips will be made around China during the 40-day Spring Festival travel rush, which started on January 24. (Photo by Jason Lee/Reuters)