Watch Series 3 Waterproof Phone Calls?

[bp2524]

What happens when if the Series 3 watch is submerged while on a phone call? For example, the keynote speaker falls off the paddle board - does the phone call get dropped? What if the girl surfing had answered that call? Would the call get dropped if she wiped out??? Serious questions, as I plan to use the watch while surfing and love the the idea of being able to check in at home.