Today's combat submarine holds a crew of less than 200 men, equal to a company of infantry. Yet these few submariners can command a sea or destroy a civilization. Never has so much combat power been wielded by so few warriors. This concentration of power is made possible by innovative use of technologies, including rocketry, acoustics, hydrodynamics, nuclear power, advanced chemistry, unique materials and a host of others. Unlike other 20th century military innovations - the tank, the airplane and nuclear explosives - the submarine remains shrouded in secrecy, a truly "silent service. " This book surveys the state of submarine technology worldwide, and examines research advances that will shape the second century of submarines.