By analysing shadows and areas of clear blue water on Google Maps, Johnny was able to identify locations for each – but they’re very hard to find, and require near-perfect tides and weather to dive them. “The importance of the next generation learning more about marine animals is paramount,” he added. “The ocean is the biggest environment that is losing its health the fastest. By finding hidden wonders like these, and keeping their locations hidden, Johnny hopes he can preserve more life while some of the damaged areas of the reef continue to recover. Explaining how a blue hole actually forms, he said: “In the Great Barrier Reef – and this is only what the geologists think, it’s not definitive – it’s believed that with the rise and fall of the sea level along the east coast of Australia, weaknesses cause big areas to fall in, creating a sink hole.

The most chilled Loggerhead I’ve met. On a solo snorkel off Coral bay, this guy came up and stayed with me for about 20 mins. I think he wanted to crunch the camera. This photo was right at the moment when he noticed himself in the reflection of the camera dome port. I like to think he posed, may have just been fluke timing… classic Loggerhead. A post shared by Marine Bio | UW Photographer (@johnny_gaskell) on Jul 22, 2017 at 7:10pm PDT “As the sea levels rise to where they are now, they fill with sea water and coral is able to grow round the edge, where there’s more sunlight. “There’s hardly any studies done on our blue holes, I don’t know why, that’s why I want to get out there. There’s a couple of really big ones that have never been dived we’ve found now.” Johnny explained corals rely on sunlight to survive, as do plankton, so the most impressive formations tended to be along the sides of blue holes that have regular sunlight streaming down.

In addition, the depth of the hole causes a sort of channel where salt water is continuously moving down in sunlight, feeding the coral and causing it to grow faster. The world’s largest known blue hole, named The Great Blue Hole, is found off the coast of Belize. The giant submarine sinkhole is 124 metres deep. Read more: 5 amazing island beaches in Queensland “The Whitsundays definitely captivated me – there are so many islands around here and they are all unique and wonderful,” he said. “Honestly, living here you never get sick of exploring new places but, on the off chance you did, you just go back to the places you love.”