Currently many scientists think that life may have begun on Earth in the vicinity of deep-oceanic, hydrothermal vents. This type of environment was anticipated by Charles Darwin, some 150 years before, who wrote:
'But if we could conceive in some warm little pond, with all sorts of ammonia and phosphoric salts, light, heat electricity etc, present'
Hydrothermal vents represent discharges of hot, sometimes super-heated water, onto the ocean floor deep beneath the surface oceans. Hydrothermal vents tend to be found close to mid-ocean ridges. It is thought that the water is heated from contact with the hot, newly-formed oceanic lithosphere of oceanic spreading centres. For more detail see http://www.ocean.washington.edu/people/grads/scottv/exploraquarium/vent/intro.htm.
Hydrothermal vents are of a number of types, but the most spectacular are 'black smokers', where mineral-laden, super-heated water is discharged into cold ocean floor water creating a black, smoke-like plume. Vents of this type were first discovered in the late 1970s with the aid of small submarines capable of operating under several kilometers of ocean water. The best known of these is the submersible ALVIN. For images of hydrothermal vents and their exploration see http://www.pmel.noaa.gov/vents/chemocean.html (then select 'image gallery').
Below, seven lines of evidence are given, which support the view that hydrothermal vents are where life first formed on Earth: