SYDNEY (AFP) - Two divers survived more than 20 hours in shark-infested waters in Australia's Great Barrier Reef before being found, rescuers said Saturday. Police said the pair, a British man and an American woman, were diving off the Whitsunday Islands Friday afternoon when they became separated from their charter boat. A search began late Friday and a helicopter spotted the pair mid-morning Saturday, about 13 km from their original dive site. They were winched to safety and taken to a local hospital, where they received treatment for mild exposure. Rescuers said the 38-year-old man and 40-year-old woman were lucky to be alive. "If I was them I'd be getting out the 30 million dollar lotto ticket tonight... they were very lucky people," RACQ Rescue helicopter spokesman Philip Dowler said. Finding the divers was a difficult proposition, he told ABC radio. "All you are looking at is a head floating in the water, you can't see their full body, and today in this area of Queensland it's quite cloudy, there's some scattered showers, about half a metre to a metre swell, so it would have been very difficult to pick up these two people." Shane Chelepy of the Queensland water police praised them for their cool thinking. "The divers made some very good decisions throughout the evening," he said. "My information from talking to them is they strapped themselves together using their weight belts, they conserved energy, stayed as a pair and awaited rescue." The pair are believed to have surfaced about 200 metres (650 feet) from their boat. The incident has echoes of the disappearance of an American couple, Tom and Eileen Lonergan, in 1998, on a diving trip to the Great Barrier Reef. In that case, it was two days before dive operators raised the alarm and no sign of the couple was ever found except for a shredded piece of Eileen Lonergan's wetsuit. A coronor's inquiry concluded they drowned or were killed by sharks and the skipper of the dive boat was charged with manslaughter and later acquitted. The case resulted in stricter safety controls on the reef's dive operators, including more regular head counts of divers. It was the basis of an Australian feature film "Open Water" in 2004.