U.S. Navy Salvage Manual(PDF). Vol. 4: Deep Ocean Operations S0300-A6-MAN-040 0910-LP-252-3200. United States. Navy Department. Supervisor of Salvage and Diving. 1 August 1993. This article incorporates text from this source, which is in the public domain.
For example, PADI regards search and recovery as one of only three speciality which require the student to already be certified as an Advanced Open Water Diver before commencing (the other two being ice diving and cave diving, both of which are considered highly hazardous).[1]