More than a mile below the choppy Gulf of Mexico waters lies a vast, untapped source of energy. Locked in mysterious crystals, the sediment beneath the seabed holds enough natural gas to fuel America's energy-guzzling society for decades, or to bring about sufficient climate change to melt the planet's glaciers and cause catastrophic flooding, depending on whom you talk to.
No prizes for guessing the US government's preferred line. This week it will dispatch a drilling vessel to the region, on a mission to bring this virtually inexhaustible new supply of fossil fuel to power stations within a decade.
The ship will hunt for methane hydrates, a weird combination of gas and water produced in the crushing pressures deep within the earth - literally, ice that burns.
The stakes could not be higher: scientists reckon there could be more valuable carbon fuel stored in the vast methane hydrate deposits scattered under the world's seabed and Arctic permafrost than in all of the known reserves of coal, oil and gas put together.
"The amount of energy there is just too big to ignore," said Bahman Tohidi, head of the centre for gas hydrate research at Heriot Watt University in Edinburgh. "It's not easy, but it's not something we can say we can't do so let's forget about it."
Britain may miss out on any future methane hydrate boom - the North Sea is too shallow and no deposits have been found in the deeper waters further north - but other countries have recognised their potential. Japan, India and Korea, as well as the United States, are investing millions of pounds in hydrate research.
Ray Boswell, who heads the hydrate programme at the US department of energy's national energy technology laboratory, said the US was determined to be the first to mine the resource.
"Commercially viable production is definitely realistic within a decade. The world is investing in hydrates, and one reason for us to do this is to maintain our leadership position in this emerging technology."
Its new project will see the drilling vessel Uncle John spend about a month in the Gulf of Mexico, where it will bore down to two of the largest expected methane hydrate deposits in the region. Scientists on the ship will collect samples for experiments to see how the methane might be freed and transported to the surface.
This is harder than it sounds. In some deposits the crystals occur in thick layers, in others they are found as smaller nuggets. Puncture one hydrate reservoir and the giant release of gas can disrupt drilling, pierce another and getting the methane out is like sucking porridge through a straw.
This unpredictable nature means energy companies traditionally view hydrates as a nuisance. This gives them a joint interest with the US government as both sides want to know where the crystals are - one to avoid them and the other to exploit them.
Mr Boswell said: "We have a marriage of near-term industry interests and longer-term government interests. If they develop the ability to detect hydrates for the purpose of avoiding them, that's useful for people who want to do the exact same thing for the purpose of finding them."
Devinder Mahajan, a chemist at the US department of energy's laboratory in Brookhaven, is looking for ways to encourage subsea hydrate deposits to release their methane. He has developed a pressurised tank that allows scientists to study hydrate formation. "You fill the vessel with water and sediment, put in methane gas and cool it down under high pressure. After a few hours, the hydrates form, you can actually see it. They look like ice, but they're not," he said. "This is a very important issue, tied to our future national energy security."
Hydrates on land are easier to get at, and in 2003 a team of oil companies and scientists from Canada, Japan, India, Germany and the US showed it was possible to produce methane from the icy deposits below Canada's Northwest Territories. BP and the US government are carrying out similar experiments in Alaska.
Environmental groups oppose attempts to extract methane from hydrate reserves.
Roger Higman, a climate change campaigner with Friends of the Earth, said: "The Americans are desperately looking around trying to boost their fossil fuels because they think the oil is going to run out or there's going to be a scarcity. The actual scarcity is in the space the atmosphere has for taking the carbon dioxide that burning methane produces."
He added: "We already have enough fossil fuel in the world that, if burnt, will ruin the world's climate. Rather than look for more, we need to keep the oil, gas and coal we already know about underground and develop alternative sources of energy, principally renewables."
Paul Johnston, a scientist in the Greenpeace laboratory at Exeter University, warned that disturbing hydrate deposits under the seabed was a risky strategy.
"There are legitimate concerns that attempts to tap into these reserves could cause very widespread destabilisation of the seabed and damage to ecosystems," he said.
Methane is a far more potent greenhouse gas than carbon dioxide, he said, and any released during production would make global warming worse.
Mr Boswell said methane was more environmentally friendly than oil and coal, because it produced less carbon dioxide when burnt.
"The prudent approach is to address all the avenues for supplying future energy," he said. "People who say it has to be one or the other, I think, are putting too many eggs in one basket."