Caroline Wozniacki of Denmark serves to Alisa Kleybanova of Russia during the BNP Paribas Open at the Indian Wells Tennis Garden on March 15, 2011 in Indian Wells, California. (Photo by Matthew Stockman/Getty Images)

An ice swimming enthusiast dressed as Neptune takes to the frigid waters of Orankesee lake during the 27th annual "Winter Swimming in Berlin" on January 8, 2011 in Berlin, Germany. A local swimmers' group called the “Berlin Seals” invite ice swimmers from across Germany and abroad to the annual event. Members claim ice swimming is good for the body's blood circulation. (Photo by Sean Gallup)

A couple dance tango for tourists at Caminito, a touristic hotspot of La Boca neighborhood in Buenos Aires, Argentina, October 15, 2016. (Photo by Enrique Marcarian/Reuters)

Spanish soldiers of the 7th Airborne Light Infantry Brigade “Galicia” fire a howitzer Light Gun L118 during maneuvers with other units in preparation to NATO's Very High Readiness Joint Task Force (VJTF) in Zaragoza, Spain, April 19, 2016. (Photo by Javier Cebollada/EPA)

People are seen near a Christmas decoration installed on city Square for the upcoming New Year and Christmas season in Skopje, Macedonia December 23, 2016. (Photo by Ognen Teofilvovski/Reuters)

Internally displaced Syrian children who fled Raqqa city stand near their tent in Ras al-Ain province, Syria January 22, 2017. (Photo by Rodi Said/Reuters)

A skier in a costume attempts to cross a pool of water at the foot of a ski slope while competing in the annual “Gornoluzhnik” amateur event marking the end of the ski season, at the Bobrovy Log ski resort in the suburbs of the Siberian city of Krasnoyarsk, Russia, April 16, 2017. (Photo by Ilya Naymushin/Reuters)

Lily Donaldson attends the “Loveless (Nelyubov)” screening during the 70th annual Cannes Film Festival at Palais des Festivals on May 18, 2017 in Cannes, France. (Photo by Tristan Fewings/Getty Images)