A transatlantic tunnel is a theoretical tunnel which would span the Atlantic Ocean between North America and Europe and would carry mass transit of some type—trains are envisioned in most proposals. Using advanced technologies, speeds of 500 to 8,000 kilometres per hour (310 to 5,000 mph) are envisaged.
Plans for such a tunnel have not progressed beyond the conceptual stage, and no one is actively pursuing such a project. Most conceptions of the tunnel have it between the United States and the United Kingdom, or more specifically, New York City and London. The main barriers to constructing such a tunnel are cost—from $175 billion to $12 trillion—and the limits of current materials science.
Existing major tunnels, such as the Channel Tunnel and Seikan Tunnel, despite using less expensive technology than proposed for the transatlantic tunnel, struggle financially.
A transatlantic tunnel would be 88 times longer than the Gotthard Base Tunnel and 36 times longer than the Delaware Aqueduct.
https://www.youtube.com/watch?v=_FZH7k7-KtM
[mappress] Subsea World News Staff, February 22, 2013