1.Oil consumption-price.The world is consuming about 90 million barrels of oil/day (Mbd).Oil prices in 07/2008 reached 145.29 USD per barrel.Oil-price in 10/2010 was 81.73 USD, today 08/2012, the Brent crude oil costs 113.25 USD per barrel.The OPECs oil excess capacity was 10 Mbd in 1995;this capacity decreased to 2 Mbod in 2008.There is no longer a safety margin to ensure oil price stability in the face of demand spikes and supply interruptions.The oil production costs in many reservoirs are increasingly high.In the very near future we will have limited oil supply,increasing demand, higher oil prices and increasing pollution.There is an urgent need to replace hydrocarbons with other, clean primary energy sources.Deep submarine offshore geothermal energy is one of these sources able to replace hydrocarbons and nuclear.2.Geothermal submarine reservoirs.Seafloor hydrothermal circulation is the principal agent of heat-mass transfer from the Earths crust to the ocean/atmosphere system.Deep submarine energy is emerging along oceanic spreading centers, which have a length of 65,000 km;they contain immense amounts of energy supporting rich biological communities.Submarine geothermal energy embraces both near-surface reservoirs at depths of 1-50 m, and deep hydrothermal resources at more than 2000 m depth.Their fluids could be at supercritical thermodynamic conditions (400C, 220 bar).These fluids could provide up to ten times as much power per m3, as the geothermal fluids used in the current technology.Supercritical geothermal resources will enable the generation of electricity on a more efficient basis through advanced supercritical turbine-generators located on the ocean floor.This paper provides a basic description of the fundamental characteristics of this enormous geothermal source, which has never been used on Earth.