Clearance Diving Team ( RAN ) The Clearance Diving Teams ( CDT ) of the Royal Australian Navy ( RAN ) also act as commando frogmen : they consist of naval personnel who are qualified in diving , demolitions , underwater repairs , and reconnaissance . They fulfil a special forces , maritime counter - terrorism role as part of the waterborne troop of the Tactical Assault Group East ( TAG EAST ) . History . The RAN has used divers on a regular basis since the 1920s , but it was not until World War II that clearance diving operations came to the fore , with RAN divers working alongside Royal Navy divers to remove naval mine s from British waters , and from the waters of captured ports on the European mainland . RAN divers were also used in the commando frogman role , performing duties including reconnaissance of amphibious landing sites . The skills learned in the European theatre were brought back to Australia , and utilised in the war against Japan . After the war , RAN divers were used during the cleanup of Australian and Papua New Guinea waters of defensive mines . The utility of clearance and commando divers demonstrated during and after World War II prompted the Australian Commonwealth Naval Board to establish a clearance diving branch within the RAN in 1951 . Divers were initially attached to the Underwater Research and Development Unit , based at . In 1956 , they were organised into a separate Mobile Clearance Diving Team . In March 1966 , the divers underwent further reorganisation , splitting into two Clearance Diving Teams . Clearance Diving Team 1 ( initially CDT 1 , later styled as AUSCDT 1 ) was the operational team assigned to mine clearance and commando operations throughout the Australia Station , while Clearance Diving Team 2 ( CDT 2 / AUSCDT 2 ) was dedicated to mine warfare in the Sydney area , but was not cleared for operations outside this area . In late 1966 , Clearance Diving Team 3 was established specifically for deployment to the Vietnam War to assist the overworked United States Navy Explosive Ordnance Disposal units , and to give RAN personnel in clearance diving work in an operational environment . Sending CDT 1 or CDT 2 , in full or in part , would have impacted on the teams ' existing commitments , along with the continuity of training and postings . CDT 3 was formed from available personnel ; this was sufficient to keep a six - man team on station in Vietnam from early 1967 until early 1971 , with six - month deployments . CDT 3 was disbanded at the end of the Vietnam War , but the designation is reactivated for overseas wartime deployments , including in 1991 for the Gulf War , and again in 2003 for the Iraq War . Units . There are two standing units based in Australia ; A third unit , Clearance Diving Team Three ( AUSCDT THREE ) is formed when clearance divers are sent into combat . CDT 3 saw extensive service in the Vietnam War , and during the 1991 Gulf War and the 2003 Iraq War . There are eight Reserve Diving Teams ( RDT ) which provide supplementary or surge capability in support of regular CDTs in addition to localised fleet underwater taskings : Role . The Clearance Divers ' roles include : 1 . Mine Counter Measures ( MCM ) and Explosive Ordnance Disposal ( EOD ) : 2 . Maritime Tactical Operations : 3 . Underwater Battle Damage Repair : 4 . Tactical Assault Group ( East ) : 5 . Counter Piracy : Selection . The RAN ' s diver training program is centred around a 10 - day clearance diver acceptance test ( CDAT ) , colloquially known as " hell week " . Recruits begin each day at 02 : 00 , and are put through over thirty staged dives designed to test their strength and endurance .