[beachy]

That's a great point, certainly you wouldn't want to breed a culture where the life guards were playing cards back in the staff room with one ear cocked for the "silent sentry" going off to warn of a drowning.

I'd probably deploy it as an almost invisible thing that the staff never interacted with, and dial its detection way down until it virtually never gave a false positive, even if that meant it missed 20% of the actual drownings (those people are no worse off). Anything to avoid complacency, even one false alarm every couple of months would be too much.

The UI would be an earsplitting siren followed by a Robocop like voice shouting e.g. "someone is drowning in lane 5, 50 meter point".

[Buttons840]

People would try to troll the system and trick it into sounding false alarms.

It's still a good idea, but just an idea at this point. There would be lots of challenges to make it work.