Add Yahoo as a preferred source to see more of our stories on Google. L. David Marquet is a former United States Navy Captain and author who served in the submarine force for nearly three decades.

Because of their stealth, operational adaptability, and capacity to project power in a way that surface ships cannot, submarines are considered one of the most important naval assets a country may ...

Imagine being sealed inside a metal tube beneath the ocean for three months straight, with no possibility of fresh supplies, ...