▁The ▁following ▁table ▁gives ▁an ▁over view ▁of ▁the ▁activities ▁that ▁various ▁ag encies ▁suggest ▁to ▁differenti ate ▁between ▁technical ▁and ▁recre ational ▁div ing : ▁ ▁Haz ards ▁and ▁risk ▁One ▁of ▁the ▁perce ived ▁differences ▁between ▁technical ▁and ▁other ▁forms ▁of ▁recre ational ▁div ing ▁is ▁the ▁associated ▁ha z ards , ▁of ▁which ▁there ▁are ▁more ▁associated ▁with ▁technical ▁div ing , ▁and ▁risk , ▁which ▁is ▁often , ▁but ▁not ▁always ▁greater ▁in ▁technical ▁div ing . ▁Haz ards ▁are ▁the ▁circumstances ▁that ▁may ▁cause ▁harm , ▁and ▁risk ▁is ▁the ▁lik elihood ▁of ▁the ▁harm ▁actually ▁occurr ing . ▁The ▁ha z ards ▁are ▁partly ▁due ▁to ▁the ▁extended ▁scope ▁of ▁technical ▁div ing , ▁and ▁partly ▁associated ▁with ▁the ▁equipment ▁used . ▁In ▁some ▁cases ▁the ▁equipment ▁used ▁presents ▁a ▁secondary ▁risk ▁while ▁mit ig ating ▁a ▁primary ▁risk , ▁such ▁as ▁the ▁complexity ▁of ▁gas ▁management ▁needed ▁to ▁reduce ▁the ▁risk ▁of ▁a ▁fatal ▁gas ▁supply ▁failure , ▁or ▁the ▁use ▁of ▁g ases ▁potentially ▁un bre ath able ▁for ▁some ▁parts ▁of ▁a ▁d ive ▁profile ▁to ▁reduce ▁the ▁risk ▁of ▁harm ▁caused ▁by ▁o xygen ▁to x icity , ▁nit ro gen ▁nar cos is ▁or ▁decom pression ▁sick ness ▁for ▁the ▁whole ▁operation . ▁Red u ction ▁of ▁secondary ▁ris ks ▁may ▁also ▁affect ▁equipment ▁choice , ▁but ▁is ▁largely ▁skill - based . ▁Training ▁of ▁technical ▁divers ▁includes ▁procedures ▁which ▁are ▁known ▁from ▁experience ▁to ▁be ▁effective ▁in ▁handling ▁the ▁most ▁common