Hell at 50 Fathoms, written by Vice Admiral Charles A. Lockwood and Colonel Hans Christian Adamson, tells the story of submarine accidents of the United States Navy. It describes the bone-chilling experiences of valiant sailors who risked their lives to perfect underwater craft. Vice Admiral Lockwood, so well-known to submariners as the World War II Commander of the Submarine Force, U.S. Pacific Fleet, has always been interested in diving and all other underwater exploits. This interest was exemplified when, in July 1943, he led a group of swimmers in the recovery of a live torpedo. The torpedo had been test fired against a cliff in an effort to discover the cause of faulty exploders. This effort was successful. The fault was disclosed and corrected, much to the relief of submarine captains who had seen so many torpedoes bounce off Japanese ships without exploding. Lockwood was awarded the Legion of Merit for this conspicuous gallantry. This is a striking example of the resourcefulness inbred in submarine sailors. Each mishap discloses a weakness that is corrected. The tragedy of the sinking of the S-4 brought forth, with stunning forcefulness, the inadequacy of our technical competency to deal with a simple rescue problem. Within the steel hull of the S-4, brave men hammered out signals pleading for help--help that never came. Using the restored S-4 as an experimental laboratory, the Navy produced dramatic results in learning how entrapped men can escape, how surface crews can rescue them, and how to salvage a submarine for further service.--C. B. Momsen, Vice Admiral, USN (Ret.)