Although Alvin, a small, deep-diving submarine, was launched in the face of doubts about its value, safety and cost-effectiveness, it has been involved in some of the most important marine missions of recent times. Alvin and its crew found and retrieved a lost H-bomb, became the first to reach the Mid-Atlantic Ridge, discovered exotic new forms of life in the warm springs of the Galapagos Rift, and sailed through the hyperthermal vents of the East Pacific Rise, where fluid deposits are hot enough to melt lead. This study of the creation of Alvin charts these and many other dives, including the most famous of them all, the location in 1985 of the wreck of the Titanic.