The Royal Australian Navy School of Underwater Medicine (RANSUM) is based at Sydney, Australia.
The Diving Section of HMAS Watson was afforded by the District Medical Officer, Surgeon Lieutenant Commander Shane A.C. Watson, whose interest in diving led to research in injuries related to marine animals. Medical Director-General of the Royal Australian Navy, Surgeon Rear Admiral Lionel Lockwood, recognized the need for a specialisation in diving medicine shown by Dr. Watson and appointed Surgeon Lieutenant Commander Rex Gray to service in Underwater Medicine. Dr. Gray was an anaesthesiologist and accepted this commission on 20 February 1961.
Dr. Gray was trained as a diver and sent to England for seven months to learn about modern diving medicine. He visited the Royal Naval Medical School at Alverstoke, the R.N. Physiological Laboratory, the Submarine Training School at HMS Dolphin, Diving School HMS Vernon, and the RN Air Medical School at Seafield Park. Following his time in England, he travelled to the United States, where he spent two weeks each in the Experimental Diving Unit, Washington Navy Yard, and with the Medical Research Laboratory, Submarine Base, New London, Connecticut, returning to Australia in July, 1962, aboard HMAS Supply.
The first School of Underwater Medicine Report was issued in 1963 and outlined the need for communication with organizations with similar interests such as carbon monoxide poisoning and recompression chambers. The first eight-day Underwater Medicine course was held in May 1963, when Surgeon Lieutenant Commander A.A. Reid, and was followed by a thirteen-day course by Surgeon Lieutenant Commander B.M. Wadham, in June 1963.
- Gray, Keith (1969). History of the RAN School of Underwater Medicine 1963–1969. Project 2–69. Royal Australian Navy, School of Underwater Medicine. Retrieved 2009-05-14.
- Technical reports from the Royal Australian Navy, School of Underwater Medicine, stored by the Rubicon Foundation