Open Water (2003)

Happy couple Daniel 'Dan' and Susan book a tropical holiday in the Caribean. They toughen out a mosquito-spoiled night after the exhausting flight, looking forward to the scuba diving next day. They enjoy it so much they're last to come up, but by then the boat has left, despite the obligatory divers count, which got upset after Seth, who forgot his mask, convinced someone to dive as regulations-required buddy with him. The current carries them away in open water, helplessly trying to attract someone's attention in vain, stung jellyfish and fearing shark attacks. Susan starts whining and absurdly blaming Dan, who feels forced to remind her that it's her's. Both are desperately exhausted by the time their disappearance gets noticed and a rescue operation by plane and boat is mounted.