The NASA Extreme Environment Mission Operations (NEEMO) 21 mission began on July 21 as an international crew of aquanauts splashed down to the undersea Aquarius Reef Base, located 62 feet below the surface of the Atlantic Ocean in the Florida Keys National Marine Sanctuary. The NEEMO 21 crew will perform research both inside and outside the habitat during a 16-day simulated space mission. During simulated spacewalks carried out underwater, they will evaluate tools and mission operation techniques that could be used in future space missions, including journeys to Mars. (Photo by Karl Shreeves/NASA)

Activists from People for the Ethical Treatment of Animals (PETA) promoting a vegan diet are pictured as people drive past in Los Angeles, California May 21, 2015. (Photo by Mario Anzuoni/Reuters)

Workers attach a hat to a pinata depicting the drug lord Joaquin “El Chapo” Guzman at a workshop in Reynosa, July 21, 2015. Guzman broke out of Mexico's top maximum security prison through a tunnel built into his cell earlier this month. (Photo by Daniel Becerril/Reuters)

Miss Lithuania, Patricija Belousova, poses for the judges, during the national costume show during the 63rd annual Miss Universe Competition in Miami, Fla., Wednesday, January 21, 2015. (Photo by J. Pat Carter/AP Photo)

A participant falls on vintage skis during a traditional historical ski race in the northern Bohemian town of Smrzovka February 21, 2015. (Photo by David W. Cerny/Reuters)

A supporter of the team of Ukraine cheers prior to the Euro 2016 Group C soccer match between Ukraine and Poland at the Velodrome stadium in Marseille, France, Tuesday, June 21, 2016. (Photo by Thanassis Stavrakis/AP Photo)

A Puffin jumps into its burrow with a mouthful of sea eels to feed its chick on Skomer Island, Pembrokeshire in Wales, Britain June 21, 2016. (Photo by Rebecca Naden/Reuters)

Girls sit inside an empty classroom as they pose for a photograph during a celebration marking the end of the school year in the town of Douma, eastern Ghouta in Damascus, Syria May 21, 2016. (Photo by Bassam Khabieh/Reuters)