Ice-like solids in which methane molecules are held within the molecular spaces of the water molecule. Can form in pipelines and wells under certain conditions of near freezing temperatures and high pressures. Their formation is averted by ensuring that water vapour levels in the gas are kept below specified levels. See also Treatment, Dew Point. Hydrates are found naturally beneath the ocean at depths greater than 300m in many areas, where they are estimated to have locked up many trillions of cubic metres of methane. There is speculation that these hydrates may provide a commercial resource in the future. Hydrates have also been proposed as a means of transporting natural gas by sea, possibly competing with LNG.