A clearance diver was originally a specialist naval diver who used explosives underwater to remove obstructions to make harbours and shipping channels safe to navigate, but later the term "clearance diver" was used to include other naval underwater work. Units of clearance divers were first formed during and after the Second World War to clear ports and harbours in the Mediterranean and Northern Europe of unexploded ordnance and shipwrecks and booby traps laid by the Germans.
The first units were Royal Navy Mine and Bomb Disposal Units. They were succeeded by the "Port Clearance Parties" (P Parties). The first operations by P Parties included clearing away the debris of unexploded ammunition left during the Normandy Invasion. During World War II Navies used the heavy surface-supplied standard diving dress before changing to lighter self-contained rebreather equipment.
Admission to clearance diver training requires the candidate to pass medical and physical fitness screening and to be a member of the relevant military force.
The scope of activity for a clearance diver varies depending on the specific armed force in which they are a member, but historically the most defining competence is skills in underwater demolition using explosives. The closely associated skills in explosive ordnance disposal are also generally implied by the designation.
Royal Navy naval work divers are officially called Clearance Divers. During WWII divers used the Davis Submerged Escape Apparatus (DSEA), no wetsuit or swimfins. On 17 December 1942, six Italian divers on three manned torpedoes attacked Gibraltar harbour. A British patrol boat killed the crew of one with a depth charge. Their bodies were recovered and their swimfins later used by Gibraltar's guard divers (Sydney Knowles and Commander Lionel Crabb). This was the first known British use of swimfins.
In November 1944, following surrender of Italian forces an Italian frogman brought two Decima Flottiglia issue oxygen rebreathers and a 2-piece frogman's drysuit to Livorno, for the Allies to use. This equipment proved better than the Davis Apparatus and lasted longer on a dive. After the war and until the 1990s divers used the Siebe Gorman rebreather and aqualung.
Training to become a Clearance Diver takes around 7 months. Before trainees are accepted onto a course, they must pass a week-long diving aptitude selection, held at the Defence Diving School, on Horsea Island, Portsmouth. This selection involves passing the Divers Physical Fitness Test (DPFT), tests of physical and mental endurance and surface swimming. The candidates are also introduced to the Royal Navy's Swimmers Air Breathing Apparatus and dive in Horsea lake, including night dives. Historically, the failure rate has been high due to the physical and psychological pressures of military diving, so there is a three-day Pre Entry Diving Acquaint (PEDA), which allows prospective candidates to undergo physical and mental tests to give them a better idea of what to expect of the training.
Clearance divers have been involved in every major British conflict since their inception and have most recently deployed teams to Iraq, Afghanistan and Libya. They have units operating in the Persian Gulf and Indian Ocean providing an underwater force protection (UWFP) element. See Operation Kipion.