A mother bear takes a dip in the water to cool off in the warm summer sun but refuses to leave her three youngsters behind – so they climb aboard her back. (Photo by Jon Langeland/Solent News & Photo Agency)

Gold medallists of China perform Synchronised Swimming Free Combination routine at the Munhak Park Tae-hwan Aquatics Center during the 17th Asian Games in Incheon September 23, 2014. (Photo by Tim Wimborne/Reuters)

Prince William exchanges rings with his bride Catherine Middleton in front of the Archbishop of Canterbury Rowan Williams inside Westminster Abbey on April 29, 2011 in London, England. The marriage of Prince William, the second in line to the British throne, to Catherine Middleton is being held in London today. The marriage of the second in line to the British throne is to be led by the Archbishop of Canterbury and will be attended by 1900 guests, including foreign Royal family members and heads of state. Thousands of well-wishers from around the world have also flocked to London to witness the spectacle and pageantry of the Royal Wedding. (Photo by Dominic Lipinski - WPA Pool/Getty Images)

Arsenal football supporters cheering from the train carriage window as they leave Euston Station, London, on their way to Birmingham for their team's match against Aston Villa which they lost 3-5. (Photo by Douglas Miller/Topical Press Agency/Getty Images). 19th November 1932

More than 700 underwater images were submitted for the 2012 Annual Underwater Photography Contest, hosted by the University of Miami's Rosenstiel School of Marine & Atmospheric Science. This year, for the first time, the University of Miami set up a “Fan Favorite” category for its underwater photo competition. Internet users could vote for their favorite among five pictures. Todd Aki's photo of a jellyfish took the prize, snaring 599 of the 1,221 votes cast. (Photo by Todd Aki)

Derrick Campana kneels beside Angel Marie, a three legged mini horse who wears a prosthetic leg made by Campana, at Animal Ortho Care in Sterling, Virginia, U.S., March 27, 2017. (Photo by Kevin Lamarque/Reuters)

In this handout photograph received from Sumukha J.N on December 15, 2016, the newly-discovered spider Eriovixia Gryffindori sits on a leaf in the Kans in India's Western Ghats. (Photo by Sumukha J.N./AFP Photo)

Protesters use fireworks against riot police during clashes in the Athens neighborhood of Exarchia, a haven for extreme leftists and anarchists, Thursday, December 6, 2018. New protest marches were underway in Greece Thursday evening on the 10th anniversary of the fatal police shooting of a teenager, hours after violent initial demonstrations where masked youths attacked police with firebombs and stones. (Photo by Yorgos Karahalis/AP Photo)