U.S. Navy Diving Manual
The U.S. Navy Diving Manual is a book used by the US Navy for diver training and diving operations. Overview. The US Navy first provided a diving manual for training and operational guidance in 1905, and the first book titled "Diving Manual" was published in 1916. Since then books titled "Diving Manual" or "U.S. Navy Diving Manual" have been published several times, each one updating the content of the previous version. The amount of information provided has tended to increase over the years, the 1905 edition had approximately 66 pages, while Revision 7 (2016) has 992  pages in 18 chapters; the manuals are illustrated with contemporary photographs, diagrams and graphs. Content. Content has varied in the various editions, and the order and layout have changed over the years. It remains one of the most comprehensive textbooks on the theory and practice of diving generally available. Some content type is common to all editions, but has been updated and expanded to keep it current and relevant, and some content has been added as the equipment, theory and field of operations changed over the more than a century of the manual's existence. Content of Revision 7. Revision  7 (2016) has the following content: Format. Varies with edition. Early editions were available in hard or soft binding. Recent editions have been casebound, looseleaf and pdf for download or on compact disc. Impact. Before the establishment of recreational diver certification, the U.S, Navy Diving Manual was used as the training manual for recreational divers in the US, and was frequently referenced in other English speaking countries. It was also used as training material for commercial divers, and has been the standard text for the U.S.Navy for diver training. US Navy decompression tables and variations on the originals have been  used worldwide by recreational and professional divers. This trend has decreased somewhat with the availability of economical and acceptably reliable decompression computers. One issue for recreational use was that the Navy decompression tables were considered relatively high risk for decompression sickness when followed to the limit. For divers without convenient recourse to a decompression chamber, this was considered an unacceptable risk, and various modifications to the tables were made for greater conservatism and convenience of use. Even after the recreational diving industry published a variety of training manuals, the U.S.Navy Diving manual remains a respected and widely used reference by  recreational technical and professional divers worldwide. This may be partly due to the ease of access, as the later versions have been freely available for download as pdf files.