▁safety ▁while ▁under water . ▁This ▁information ▁( s ic ) ▁may ▁be ▁employed ▁in ▁either ▁shall ow ▁or ▁deep ▁water , ▁may ▁be ▁used ▁to ▁safely ▁extend ▁the ▁divers ▁sub mer ged ▁duration ▁well ▁into ▁the ▁real ms ▁of ▁extended ▁decom press ions ▁and ▁is ▁often ▁used ▁as ▁a ▁tool ▁for ▁expl oration ." ▁in ▁their ▁Ex pl oration ▁and ▁M ixed ▁Gas ▁D iving ▁Encyclopedia ▁ ▁NA UI ' s ▁definition ▁of ▁technical ▁div ing ▁states : ▁" Te chn ical ▁div ing ▁is ▁a ▁form ▁of ▁sc uba ▁div ing ▁that ▁exceed s ▁the ▁typical ▁recre ational ▁limits ▁im posed ▁on ▁depth ▁and ▁imm ersion ▁time ▁( bottom ▁time ). ▁T ec ▁div ing ▁involves ▁acceler ated ▁decom pression ▁and / or ▁the ▁use ▁of ▁variable ▁gas ▁mi xt ures ▁during ▁a ▁d ive ." ▁ ▁NO AA ▁defines ▁technical ▁div ing ▁as ▁" all ▁div ing ▁methods ▁that ▁exceed ▁the ▁limits ▁im posed ▁on ▁depth ▁and / or ▁imm ersion ▁time ▁for ▁recre ational ▁sc uba ▁div ing . ▁Techn ical ▁div ing ▁often ▁involves ▁the ▁use ▁of ▁special ▁gas ▁mi xt ures ▁( other ▁than ▁com pressed ▁air ) ▁for ▁breath ing . ▁The ▁type ▁of ▁gas ▁mixture ▁used ▁is ▁determined ▁either ▁by ▁the ▁maximum ▁depth ▁planned ▁for ▁the ▁d ive , ▁or ▁by ▁the ▁length ▁of ▁time ▁that ▁the ▁diver ▁int ends ▁to ▁spend ▁under water . ▁While ▁the ▁recommended ▁maximum ▁depth ▁for ▁conventional ▁sc uba ▁div ing ▁is ▁ 1 3 0   ft , ▁technical