The number of submarines in the world's navies shrank by nearly half during the 1990s and has continued to decline at a reduced rate. Yet even the existing numbers are often overstated in speeches and articles advocating various programs and systems. Bean counting, or order-of-battle, is a respectable, necessary, and yet often misused function for determining the relative strengths of military forces. A mere listing of unit numbers cannot provide the full measure of a country's overall military capabilities or of the technical capabilities, material condition, or state of operational training of its forces. In discussions of naval forces, fleet strength is nonetheless all too often used as a valid measure of total fleet capability by senior officers, politicians, and defense analysts who should know better.
The table represents the state of the submarine fleets - as of I May 2007 - of the 43 nations that operate submarines ranging from tiny midget boats more dangerous to their own crews than to any potential target to modern, diverse fleets employing the latest in undersea technologies. The fleets are listed by type of submarine and by classes, while the Builder column indicates the country of origin. When two countries are listed, the first is the design originator and supplier of critical components, the second is the ship's assembly site. Operational totals do not include submarines undergoing pre-operational trials or those that have been long non-operational for lack of repair or refit resources but are still listed as potential assets; these are noted in the Class and Remarks column. This column also provides additional information on the status of ongoing acquisition programs and impending retirements, AIP indicates an air-independent propulsion system. The information employed in compiling the table was derived from official and authoritative unofficial sources.