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.
Women in Olympia lighting the torch
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.
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 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.
World's first underwater Olympic torch
The Pains Wessex Australia team of four pyrotechnics specialists spent six months developing the underwater burning flare that has been designed to fit into the boomerang-shaped Sydney 2000 Olympic torch.
On the 27th of June 2000, history was made at the Great Barrier Reef, Queensland, when the land-relayed Olympic flame was transferred to the special flare torch and taken underwater by the SCUBA diver to a depth of 4 metres for the historic 3 minute undersea section along the Agincourt Reef.
At the completion of the underwater swim, the diver resurfaced, ignited the next recipient’s gas fired torch, allowing the Olympic flame to continue on its epic relay to Sydney.
Design Requirements
The main achievements included developing a chemical formulation that produced environmentally acceptable by-products from combustion. The flare had to be capable of generating enough output gas pressure to prevent sea water from entering the tube and extinguishing the flame. The flare also had to generate sufficient oxygen from the chemical components to allow the main light producing fuel (magnesium) to burn smoothly in a gas envelope, producing a very bright flame visible underwater.
Testing
Several flare designs, using over 25 different flare formulations, were extensively tested underwater at various depths and swimming speeds. The trials were conducted in Corio Bay and at the Pains Wessex factory, Lara, Victoria. Special chemical preparation and mixing techniques were needed to manufacture the most effective formulation, and finally a hydraulic press was used to consolidate the mix inside each flare tube at a load of 1.5 tons.
Technical Data
The Underwater Flare will operate to a depth of 4 metres for 3 minutes. It produces an above-water light intensity of 35000 candlepower while burning at over 2000ºC.