A view inside nuclear and diesel propelled submarines, and the daily lives of their crews who require special training and continuous rehearsal to mantain readiness and safety. Interviews with captains about their duties and responsabilities. Demonstration of search and destroy tactics of underwater warfare. Finally a brief history of submarine warfare from the American Revolution to the conflict in the Falkland Islands, including film clips of submarines from the U.S., Soviet, British and German navies in action.