Naval Diving Unit ( Singapore ) The Naval Diving Unit ( NDU ) is a Special Forces unit of the Republic of Singapore Navy , and is regularly tasked in salvage operations , underwater mine demolition and commando - type warfare . History . The Naval Diving Unit ( NDU ) began with the British government ' s directive to withdraw her forces east of the Suez in 1971 . Prior to that , a unit called the Far East Fleet Clearance Diving Team was operating from the old Terror Camp premises where NDU now stands . This unit basically supported the strong British naval presence in Singapore . When the Royal Navy left on 12 December 1971 , the Far East Fleet Clearance Diving Team was replaced by the SAF Diving Center which comprised a small group of local divers tasked to look after the naval assets belonging to the then Maritime Command . In 1975 , the SAF Diving Center became officially known as the Naval Diving Unit . During the initial period , the main task of NDU was to carry out simple underwater tasks like hull checks for the Fleet . As the only public diving capability available in Singapore , divers were and still are called upon to conduct civilian diving recovery tasks . The NDU of today has its origins in the mid 80 ' s when it was realised that underwater explosive ordnance disposal ( EOD ) and keeping Singapore ' s waterways open were vital . The RSN Fleet had also grown significantly and more divers were now needed to support ships in harbour and on overseas deployments . While the NDU of the 90 ' s is almost totally unrecognisable from its humble beginnings , traces of the history of NDU can still be found , such as the British 10 - man chamber now with the Naval Medical and Hyperbaric Center . Recruitment . In NDU , NSFs and regulars are expected to undergo the same training before they are qualified to become frogmen . Recruitment begins with a vocational assessment , whereby NSFs are selected among the thousands that enlist each year . Prior to being even selected for the vocational assessment , physical fitness results and medical records are being evaluated and only the best are selected . Basic requirements are perfect eyesight , which explains the absence of people wearing spectacles in NDU , and tip top health condition , not suffering from any chronic illnesses that might jeopardise their training , such as asthma . From then on , the selected few will undergo a battery of tests in the camp , amongst them , water confidence as well as psychological evaluation . Those that meet all of these stringent requirements will then be selected to the NDU , which takes precedence over all other units and formations in Singapore . Organization . Commander : Colonel Tan Tai Tiong Dive School This is the place where trainees undergo the specialised training required to be a frogman . Here , they will undergo 9 months of grueling training , including Basic Military Training ( BMT ) , Land Combat Training ( LCT ) , followed by Combat Diver Course ( CDC ) . Advancing through the different stages , increasing amount of people drop out from the course as they are unable to keep up with the intense physical and mental demands required of them . Trainees are given lesser amount of sleep as the training goes on and numerous vetoes are set in place , which trainees are required to pass before they qualify to be a naval diver . Vetoes includes timed run , sea swim , IPPT , among others . All these training culminates to the final evolution , Team Building Week ( TBW ) , more commonly known as Hell Week . TBW is an intensive 5 day exercise whereby sleep deprivation and non - stop physical and mental exertion are commonplace . This is to separate the man from the boys , the tough from the weak . Only the most motivated and dedicated trainee , which exhibits outstanding team work and spirit is allowed to pass this final test . By the end of the 9 month training , as many as 50 % of the initial batch will not make it through as a naval diver . Following this , they are then sent to either the Underwater Demolition Group ( UDG ) or Clearance Diving Group ( CDG ) . Underwater Demolition Group This is where the bulk of the trainees go , and further training takes place here . Here , naval divers are sent overseas for further training and upgrading of skills . Clearance Diving Group Special Warfare Group Training . Basic training includes : Drown - proofing has its roots from the Vietnam War when it was found that captured U . S Navy SEALS were thrown into rivers with their hands and legs bound , and thus drown as they were not trained in drown proofing . Drown proofing teaches NDU divers to swim with their hands and legs tied . Pool competency is a module to test the divers ' water confidence , as well as their ability to keep calm under hectic situations . There are 3 parts to pool competency but is mainly being ' attacked under water . The diver ' s face mask and regulator will be ripped out and depending on the stage of the test , tied onto his air cylinder . Shoulder straps will be unraveled and the waist belt will be unbuckled . To pass the test , the diver will have to hold his breath throughout this incident and remedy the situation by getting back his air source and donning the air cylinder in the proper manner . Divers also go through a " Team Building Week " , more infamously known as " Hell Week " , where divers are pushed to their ultimate limits , going through evolutions such as cold treatment and 3 km night paddling , while receiving only minimal hours of sleep , sometimes only 3 hours collectively over 5 days . After " Hell Week " , they will be nearing the end of their 9 - month combat diver course . NDU divers are also regularly sent overseas for training , in particular , with the US Army Special Forces ( Green Berets ) , US Navy SEAL s and the British Special Air Service . In 2001 , naval officer Captain Wong Foo Chan became the first foreigner to top his class in the Green Berets course , and received a commendation medal for this achievement . He had also completed the Navy SEAL course in 1999 . NDU divers were sent to conduct salvage operations after the crash of SilkAir Flight MI185 on 19 December 1997 , which killed all 104 people on board .