Participants cross cold and muddy waters during the Strong Race competition near Tukums May 4, 2014. About 6500 people competed in this extreme running race, which includes cross-country running, elements of agility and power discipline. (Photo by Ints Kalnins/Reuters)

A general view of the ghost town of a former Soviet military radar station near Skrunda, Latvia, April 9, 2016. (Photo by Ints Kalnins/Reuters)

People wear costumes as they participate in the ancient Yule Log dragging tradition during winter solstice celebrations in Riga, Latvia, December 21, 2015. (Photo by Ints Kalnins/Reuters)

Participants compete during the Strong Race event near Tukums, Latvia, May 3, 2015. More than 4,000 people participated in this 9 km endurance race with 33 different obstacles. (Photo by Ints Kalnins/Reuters)

People use snowshoes during a tour of the Great Kemeri Bog, Latvia, October 17, 2015. The Kemeri bog is more than 8,000 years old and is one of the largest dry moss swamps in the Baltics. A more than decade-long joint restoration of the bog by the European Union and the Latvian government helped the bog recover its high moss marshes, damp black alder forests, floodplain meadows and seaside lakes – features now considered rare in Europe due to industrialisation. (Photo by Ints Kalnins/Reuters)

A vintage military aircraft is seen parked ahead of the International Air and Space Fair (FIDAE) at the Arturo Merino Benitez international airport in Santiago, Chile March 29, 2016. (Photo by Rodrigo Garrido/Reuters)

Steve Shirts, aka “Strike Pony”, left, gets a hug from Amber Snyder, aka “Ditsy Dots” in Baltimore, MD on July 8, 2016. Both are from Suburban Chicago. BronyCon is the world's largest My Pretty Pony convention. Featuring cosplay and fan events, the annual convention was held at the Baltimore Convention Center. (Photo by Andre Chung/The Washington Post)

Humanoid robots compete in a group match of the 20th RoboCup in Leipzig, Germany, June 30, 2016. About 3,500 participants from 45 countries and regions compete in the robot world championship until 04 July. (Photo by Sebastian Willnow/EPA)