Corrected entry: Why did Costner's character have to use that timer thing to gauge how long he is underwater? He has gills so he should be able to breathe underwater therefore he wouldn't have to limit his exploring time so much.
EMTurbo
12th Jan 2004
Waterworld (1995)
Correction: My theory on this is so he can make sure his awesome boat isn't left unattended for too long but that's just my thoughts.
Correction: Considering how scarce fresh water is and how easy it is to desalinate seawater, there could be chemicals in the sea after the war. Maybe the he sets the timer because he knows that staying down much longer will make him sick.
Correction: Could be he was timing for the sleeping cycle of the large sea creatures roaming the oceans. He doesn't want to be caught so deep when those things show up.
Correction: The timer was to trigger the winch to pull up all the loot.