Snorkelling in the shallow waters of the Bora Bora lagoon, Moorea, French Polynesia. (Photo by Sergi Reboredo/SIPA USA/PA Images)





A green sea turtle swims through a coral nursery in Florida, where scientists at the Coral Restoration Foundation are attempting to save reefs by growing corals that can then be replanted. (Photo by Alexander Neufeld/Coral Restoration Foundation)





Spawning silver and pink salmon stranded by low tide lie rotting along a creek in Valdez in south-central Alaska. (Photo by Ray Bulson/Alamy Stock Photo)





Stingray fish is seen on the seabed at the Samandag Cevlik Akcay diving site off the coasts of Samandag, near the Turkey-Syria border, in Hatay province of Turkey on November 10, 2018. Samandag is becoming a popular destination among divers as its provides rich underwater scenery. (Photo by Sebnem Coskun/Anadolu Agency/Getty Images)





In this September 5, 2018, file photo a lobster walks over the top of a lobster trap off the coast of Biddeford, Maine. Heavy demand from Canada is buoying the American lobster industry as both countries head into the busy holiday export season. It's a positive sign for the U.S. seafood dealers and fishermen even as the industry struggles with Chinese tariffs. (Photo by Robert F. Bukaty/AP Photo)





Split-view of a killer whale at sunrise off the coast of Northern Norway. At least half of the world’s killer whale populations are doomed to extinction due to pollution of the oceans, a new study says. (Photo by Audun Rikardsen/Science)





A shark swims above a school of sardines as they make their way across the ocean to their mating grounds. South Africa’s sardine run occurs annually from May to July when billions of sardines move northwards along the east coast of South Africa to their spawning grounds. This movement is one of the largest on the planet and attracts many predators including many species of sharks, whales and birds that follow the run to feed on the sardines. (Photo by David Robinson/Caters News Agency)





This picture taken on September 6, 2018 shows a white moray eel swimming through corals in the Egyptian Red Sea marine reserve of Ras Mohamed, off the southern tip of the Sinai peninsula. (Photo by Emily Irving-Swift/AFP Photo)





Sardines form a “baitball” under the surface of the water after being tracked by a mega pod of dolphins on the annual sardine run, the biggest migration of marine wildlife on the planet, in Port Elizabeth, South Africa. Forming a spiral formation around the fish, the dolphins were able to compress the baitball by surrounding it anticlockwise, gradually reducing the circle more and more. (Photo by Rainer Schimpf/Barcroft Images)





In this September 29, 2018 photo, sea lions swim near the Palomino Islands off the coast of Lima, Peru. Sea lions bathe and feast on the abundant fish that thrive in the cold-water Humboldt current. (Photo by Rodrigo Abd/AP Photo)





The spiral rotation not only confused the sardines but also prevented them from escaping. Bryde’s whales joined in, while gannets and other birds dove down from above. Dusky sharks and bronze whaler sharks also got their cut, swimming up from below the baitball. (Photo by Silke Schimpf/Barcroft Images)





In this February 1, 2018, images made from video and supplied by Dr Regina Eisert and Anthony Powell of the University of Canterbury a minke whale glides under the ice in McMurdo Sound, Antarctica. Marine mammal expert Regina Eisert thought minke whales were a little boring until she captured some striking footage of one swimming underwater near Antarctica. Now she thinks they're beautiful. (Photo by Regina Eisert/University of Canterbury via AP Photo)





These stunning picture shows a remarkable interaction with a playful humpback whale. Taken by Sydney-based underwater photographer David Edgar in Tonga, they show the adolescent male seemingly frollicking with David's group, which included his wife Alice. Where: Tonga When: July 14, 2018. (Photo by David Edgar/Cover Images)





Getting up close and personal with a shark is like second nature for these divers, as they enjoy a playful swim with the creatures off the coast of Palm Beach, Florida. Captured by diver and photographer, Leigh Cobb, the images show Ryan Walton as he holds the noses of some of the Lemon sharks, clearly demonstrating that the sharks love to play. Leigh said: Although Im an experienced diver I still need to keep my wits about me as these are wild animals and there are no cages for us and no training involved. Pic taken on February 3, 2017. (Photo by Leigh Cobb/Caters News Agency)





An underwater photographer has snapped the first sighting in 16 years of manta rays on a small island off the coast of Mexico. Nick Polanszky, 31, has been interested in marine life since a young age and started underwater photography five years ago. The photos were taken over the course of three months from June this year at La Reina, an island in the Sea of Cortez off the coast of Baja California Sur. Here: Divers swim alongside the giant Manta Rays. (Photo by Nick Polanszky/Caters News Agency)