This is an excellent book for the serious student of submarine history. It is perhaps the most authoritative reference book on the subject of post WWII submarines. Not only is it detailed and fully illustrated, it contains excellent tables comparing performance, size, etc. of various American submarine classes. One of its most valuable features is its descriptions of the performance characteristics of each generation of submarine and descriptions of how the designers of each successive generation attempted to improve performance. It explores, in depth, the characteristics of various generations of submarine devices, most notably sonar. It is fully footnoted and the footnotes often contain remarkable bits of info.