Olympic flame goes underwater

The torch spent three minutes in a popular diving spot

The Olympic flame has made its first ever journey underwater when it was taken to Australia's Great Barrier Reef on Tuesday.

Powered by a special chemical formula, the torch spent three minutes submerged at a popular diving spot.

A more traditional ignition at the ancient site of Olympia, Greece

Runners carried the torch to a boat at the pier in the town of Port Douglas, where it was placed in a temporary cauldron and then taken to Agincourt Reef.

Marine biologist Wendy Craig Duncan, dressed in a silver wetsuit, swam with the torch on the reef.

Special flare

The special flare was developed after nine months by a team of chemists and engineers at Melbourne pyrotechnics company Pains Wessex.

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The company's managing director Charles Tegner said designing the torch was a challenge - not only to produce a flare to burn underwater at such a depth, but to burn like the Olympic torch flame as well.

"It had to be clearly visible," he said. "Such flares don't normally exist."

The flare's chemical composition, pressed into a steel tube, produces sufficient oxygen and nitrogen to maintain a very hot flame.

The flare burns so fiercely at more than 2,000 degrees Celsius that this creates enough pressure to keep the water from entering the tube.

Its intensity is produced by a mix of oxygen-generating chemicals as well as the combustible element magnesium in a finely powdered form.

The flare burns at more than 2,000 degrees Celsius

The deep sea trip was part of the Olympic flame's longest journey that will span over 100 days and 27,000km.

The torch's tour of Australia culminates in its arrival on 15 September at the Olympic stadium in Sydney for the opening ceremony.

The flame, which has travelled through 12 Pacific nations after ignition in Greece, arrived in Australia on 8 June.

Its last leg will be an overland journey from the sacred aboriginal site Ayers' Rock to the opening ceremony in Sydney.