My kid took his Bounce swimming, and I notice that it looks like it didn't count the time as activity minutes. He's had trouble with the watch not counting lengths, so he manually hits the lap counter when he remembers, and counted 63 lengths. I suspect he did more than that, and was swimming for over 2 hours (he would have been swimming the whole time, this wasn't a "family swim" kind of activity). He started swimming at 2:30 pm, and you can see from the plot that the watch detected he wasn't moving at all during that time.
I get that it only auto-detects activity using the pedometer function, but surely if a kid tracks an activity it should count?