Participants compete in the Mud Day Race extreme run competition at El Goloso military base, outside Madrid, Spain, June 11, 2016. Thousands of athletes got covered in mud as they celebrated International Mud Day running a 13-kilometer obstacle course on a sunny Saturday with heatwave-like temperatures up to a 29 degrees Celcius (around 84 degrees Fahrenheit). (Photo by Juan Medina/Reuters)

A Common seal named Groot is prepared for release in a transfer cage at Seal Rescue Ireland wildlife sanctuary where two rescued and rehabilitated seals are released back into the sea after months of care in Wexford, Ireland, June 12, 2016. (Photo by Clodagh Kilcoyne/Reuters)

The symbol for “One Orlando” is spelled out at a makeshift memorial at Lake Eola in downtown Orlando, Fla., Saturday, June 18, 2016. Nearby, visitors lit candles and prayed at a larger memorial, at the Dr. Phillips Center for the Performing Arts, to mourn the victims of the Pulse massacre. (Photo by Joe Burbank/Orlando Sentinel via AP Photo)

A participant dressed as a mermaid goes to swim in the beach after taking part in the Annual Mermaid Parade in Brooklyn, New York, June 18, 2016. The annual parade, founded in 1983, seeks to bring mythology to life for residents, create confidence in the district and to allow artistic self-expression in public, according to the parade's website. (Photo by Eduardo Munoz/Reuters)

Wildlife photographer Danté Fenolio has headed into areas untouched by sunlight – deep seas, caves and underground – and found creatures that are exploding with colour. Here: The golden harlequin toad has vanished from the wild, and only a small number live on in captivity. A fungus caused them, and many other amphibians, to die out in their home in Central America. (Photo by Danté Fenolio/The Guardian/Johns Hopkins University Press)

Scientist Jiri Sindelar checks a ring of a Boreal owl chick outside the “Smart Nest Box”, which allows the study of birds by using mounted cameras, in a forest near the village of Mikulov, Czech Republic, June 18, 2016. (Photo by David W. Cerny/Reuters)

Sandra Brown, 40, rides the Skyslide on the 69th and 70th floors of the U.S. Bank Tower which is attached to the OUE Skyspace LA observation deck in downtown Los Angeles, California, U.S. June 20, 2016. (Photo by Lucy Nicholson/Reuters)

Mirlene Verdieu watches television as she rests in a room at the Hospital of the State University of Haiti, which is one of the centers affected by a three-month-long strike by health workers demanding a pay rise and resources, in Port-au-Prince, Haiti, June 20, 2016. (Photo by Andres Martinez Casares/Reuters)