"The famous actress and world champion in Free Dive, Marina Kazankova, presents probably the most beautiful and wonderful reef in the world: The Great Barrier Reef in Australia. Threatened by the ongoing global warming and acidification of the ocean, she fights for the preservation of this unique and UNESCO declared world natural heritage. She takes us on an extraordinary journey from Hardy Reef to the Whitsunday Islands and the unique Coral Cays. She is accompanied by a variety of reef life forms such as whale sharks, turtles and the rare giant grouper, up to three meters long. Once again we experience the underwater world of the world's largest reef, worthy of protection, with its hidden caves, mysterious shipwrecks and fantastic-looking horizontal waterfalls. Every single one of these extraordinary dives was captured with six 4K cameras and additional 4K underwater drones."