▁lo cks ▁them ▁in ▁and ▁activ ates ▁it , ▁building ▁greater ▁and ▁greater ▁pressure . ▁The ▁creature ▁k ills ▁Pen ist on . ▁Ch ase ▁allows ▁the ▁pressure ▁to ▁build ▁up ▁very ▁high ▁then ▁sm ash es ▁the ▁window ▁causing ▁all ▁the ▁air ▁to ▁come ▁out . ▁This ▁causes ▁explos ive ▁decom pression ▁and ▁the ▁creature ▁expl odes , ▁finally ▁killing ▁it . ▁Later , ▁the ▁surv iv ors ▁walk ▁into ▁the ▁sun ▁set ▁ready ▁to ▁board ▁the ▁boat , ▁pres umably ▁to ▁go ▁back ▁to ▁town ▁and ▁never ▁return ▁to ▁the ▁island . ▁ ▁Cast ▁and ▁characters ▁Craig ▁T . ▁Nelson ▁as ▁Dr . ▁Simon ▁Ch ase . ▁He ▁is ▁a ▁scient ist ▁who ▁studies ▁sh arks . ▁He ▁is ▁the ▁first ▁person ▁to ▁realize ▁the ▁creature ▁is ▁not ▁an ▁average ▁sh ark . ▁Kim ▁C attr all ▁as ▁Dr . ▁Am anda ▁M acy , ▁ex - w ife / friend ▁of ▁Dr . ▁Ch ase ▁Col m ▁Fe ore ▁as ▁Ad m . ▁Anthony ▁" T ony " ▁Rich land , ▁a ▁government ▁agent ▁who ▁attempts ▁to ▁kill ▁the ▁creature . ▁He ▁was ▁there ▁when ▁the ▁creature ▁escaped ▁and ▁was ▁attacked . ▁He ▁has ▁a ▁personal ▁vend etta ▁against ▁the ▁creature . ▁C ress ▁Williams ▁as ▁T all ▁Man , ▁Dr . ▁Ch ase ' s ▁assistant ▁and ▁close ▁friend . ▁Michael ▁Re illy ▁Bur ke ▁as ▁Adam ow icz ▁" Ad am " ▁P uck ett , ▁an ▁am bit ious ▁fish erman . ▁He ▁had ▁a ▁rival ry