List of United States submarine classes
Submarines of the United States Navy are built in classes, using a single design for a number of boats. Minor variations occur as improvements are incorporated into the design, so later boats of a class may be more capable than earlier. Also, boats are modified, sometimes extensively, while in service, creating departures from the class standard. However, in general, all boats of a class are noticeably similar.
Occasionally, a class will consist of a single ship as a protoype, or for experimental use; an example is USS Albacore (AGSS-569), which used an unprecedented hull design. In this list such single boat 'classes' are marked with '(unique)'.
