Almost from the first days of seafaring, men have used ships for “spying” and intelligence collection. Since early in the twentieth century, with the technological advancements of radio and radar, the U.S. Navy and other government agencies and many other navies have used increasingly specialized ships and submarines to ferret out the secrets of other nations. The United States and the Soviet Union/Russia have been the leaders in those efforts, especially during the forty-five years of the Cold War. But, as Norman Polmar and Lee J. Mathers reveal, so has China, which has become a major maritime power in the twenty-first century, with special interests in the South China Sea and with increasing hostility toward the United States. Through extensive, meticulous research and through the lens of such notorious spy ship events as the Israeli attack on the USS Liberty, the North Korean capture of the USS Pueblo, and the U.S. Central Intelligence Agency’s success in clandestinely salvaging part of a Soviet submarine with the Hughes Glomar Explorer, Spy Ships is a fascinating and valuable resource for understanding maritime intelligence collection and what we have learned from it.