Kate looks unrecognisable in the clip, sporting a wetsuit, flippers, goggles and a snorkel, and with her long hair tied back in a ponytail. There was one distinguishing feature, however, that gave away the Princess’ identity.

Royal fans were surprised to see Kate was still wearing her priceless sapphire engagement ring, which once belonged to Princess Diana, as she explored the reef.

Coral Vita was the winner of the 2021 Earthshot prize in the Revive Our Oceans category. The Grand Bahama-based company uses coral farming methods to design and build technology to help restore reefs across the world.

Speaking about the purpose of diving to see the project’s work in action, William said: “Being able to see the good coral and the degraded coral and understanding the difference between the two and what needs to go where — I think that was really fascinating for me to finally understand,” he said. “It’s quite technical, the way they do the coral farming and research, so I think to actually see it all being screwed in and built up is really fantastic.”

Both William and Kate are both, with the Princess becoming a qualified diver in 2015. At the time, she successfully completed the Professional Association of Diving Instructors (PADI) Advanced Open Water Diver qualification, meaning the mother-of-three is able to dive up to a depth of 30 metres.

Kate’s family, the Middletons, regularly holiday in Mustique, where William has gone on deep dives to look for sharks. It is thought that Kate earned her qualification from a diving school in the private Caribbean island.

William, meanwhile, is a very experienced diver and took over from his father King Charles to become president of the British Sub-Aqua Club (BSAC) in 2014.