▁g ases ▁from ▁their ▁body ▁during ▁as cent ▁to ▁the ▁surface ▁to ▁reduce ▁the ▁risk ▁of ▁decom pression ▁sick ness . ▁In ▁a ▁decom pression ▁d ive , ▁the ▁decom pression ▁phase ▁may ▁make ▁up ▁a ▁large ▁part ▁of ▁the ▁time ▁spent ▁under water ▁( in ▁many ▁cases ▁it ▁is ▁longer ▁than ▁the ▁actual ▁time ▁spent ▁at ▁depth ). ▁ ▁The ▁depth ▁and ▁duration ▁of ▁each ▁stop ▁is ▁dependent ▁on ▁many ▁factors , ▁primarily ▁the ▁profile ▁of ▁depth ▁and ▁time ▁of ▁the ▁d ive , ▁but ▁also ▁the ▁breath ing ▁gas ▁mix , ▁the ▁interval ▁since ▁the ▁previous ▁d ive ▁and ▁the ▁alt itude ▁of ▁the ▁d ive ▁site . ▁The ▁diver ▁obtain s ▁the ▁depth ▁and ▁duration ▁of ▁each ▁stop ▁from ▁a ▁d ive ▁computer , ▁decom pression ▁tables ▁or ▁d ive ▁planning ▁computer ▁software . ▁A ▁technical ▁sc uba ▁diver ▁will ▁typically ▁prepare ▁more ▁than ▁one ▁decom pression ▁schedule ▁to ▁plan ▁for ▁cont ingen cies ▁such ▁as ▁going ▁deeper ▁than ▁planned ▁or ▁sp ending ▁longer ▁at ▁depth ▁than ▁planned . ▁Rec re ational ▁divers ▁often ▁rely ▁on ▁a ▁personal ▁d ive ▁computer ▁to ▁allow ▁them ▁to ▁avoid ▁oblig atory ▁decom pression , ▁while ▁allowing ▁considerable ▁flex ibility ▁of ▁d ive ▁profile . ▁A ▁surface ▁supplied ▁diver ▁will ▁normally ▁have ▁a ▁div ing ▁super visor ▁at ▁the ▁control ▁point ▁who ▁mon itors ▁the ▁d ive ▁profile ▁and ▁can ▁adjust ▁the ▁schedule ▁to ▁suit ▁any ▁cont ingen cies ▁as ▁they ▁occur . ▁ ▁Miss ed ▁stops ▁ ▁A ▁diver ▁missing ▁a ▁required ▁decom