A transatlantic tunnel is a theoretical tunnel that would span the Atlantic Ocean between North America and Europe possibly for such purposes as mass transit. Some proposals envision technologically advanced trains reaching speeds of 500 to 8,000 kilometres per hour (310 to 4,970 mph). Most conceptions of the tunnel envision it between the United States and the United Kingdom ‒ or more specifically between New York City and London. Advantages compared to air travel could be increased speed, and use of electricity instead of scarce oil based fuel, considering a future time long after peak oil.