Scuba diving with a smart watch??
Unless you're tech diving and tracking run time against your deco schedule, most people generally use some kind of dive computer rather than a watch. You'd have to take it off anyway to get your arm through the wetsuit / drysuit sleeve. And given large mound of kit needed for diving you're not saving much in the way of weight or hassle.
Even when tech diving, I used to use a Suunto (plus a spare, depending on what I was doing) in guage mode as having depth and time in the same place was useful.
Not sure that criticising a smartwatch for not being able to survive a scuba dive is that fair a criticism !