Category: submarines...

U-boat is the same as submarine, German for unterseeboot
nuclear-powered submarines are capable of remaining underwater for months at a time
going down in a submarine for a deep-sea mission
The Turtle, a one-man craft invented by David Bushnell, a student at Yale, was built of wood in the shape of a walnut standing on end - designed for attacking British warships in the American Revolution
In the long course of history, having people who understand your thoughts is much greater security than another submarine. (J. Wm. Fulbright)
O God, thy sea is so great, and my boat is so small. (prayer of Breton fishermen)
The Museum of Science and Industry invites you to step inside the real U-505 - the only German submarine in the United States, and, now, a national memorial to the 55,000 American sailors who gave their lives on the high seas in WWI and WWII.