200 Meters is the standard water resistant rating for watches that you can dive or snorkel with without having to worry about them leaking.
I have a couple of Citizen Eco-Drives that have the 200M rating, titanium, run on light power, never need to be wound, account for leap years, etc.
I live in Florida so I need a watch that I don’t have to worry about getting wet, the Citizen costs about $300-400.
The Apple watch starting at about $500 isn’t cheap, so wearing it in the water at the beach or pool even isn’t advisable.
The Apple Watch starts at $349, not $500. It has the same water resistance rating as the Samsung Gear 2 and Gear S and most other smart watches. They aren't built as dive watches. Do strive for accuracy.
Well, maybe for those very few who dive and snorkel under 200 meters, the Apple Watch is not for them. Or, they could take off the Apple watch and leave it on the boat.