Heugh Breakwater by Caroline Walker. Winner in the Coastal Views category. (Photo by Caroline Walker/Sea View Photography Competition 2020)

A Sydney Aquarium diver uses a vacuum to clean the gravel in the Great Barrier Reef tank as a Ray Shark swims by September 26, 2006 in Sydney, Australia. The Aquarium is undergoing its annual spring clean to prepare for the school holidays using vacuums, along with sea creatures like Sea Cucumbers, Sea Urchins, Cleaner Wrasse Fish and Sea Stars to help complete the job. (Photo by Ian Waldie/Getty Images)

Impressive images of these alien-like creatures were captured underwater – photographer Cai Songda is a keen diver and did not miss the chance to snap pictures of the unique “aliens”. Here: A Tremoctopus Gracilis in the waters around Anilao, Philippines. (Photo by Cai Songda/Caters News Agency)

South Korean divers prepare to plunge through a hole in the ice of the frozen Imjin River on January 16, 2005 in Yeonchun, South Korea. (Photo by Chung Sung-Jun/Getty Images)

Syrian refugee and Olympic swimmer Yusra Mardini is pictured during a training session in a pool at the Olympic park in Berlin, Germany on April 26, 2018. (Photo by Fabrizio Bensch/Reuters)

The carcass of a fattened pig, winner of the “holy pig” contest, is attached to a metal frame during a sacrificial ceremony in Sanxia district, in New Taipei City, Taiwan February 1, 2017. The winner of Taiwan's “holy pig” ceremony on Thursday defended the lunar new year tradition against critics who argue the fattened animals are raised under cruel conditions. (Photo by Tyrone Siu/Reuters)

The overall winner of the 2013 Red Bull Illume photography competition from Lorenz Holder. (Photo by Lorenz Holder/Red Bull)

Youth category winner: Symphony No 5 by Giacomo Redaelli (Italy). (Photo by Giacomo Redaelli/2019 Nature Photographer of the Year)