I'm planning a sailing trip for next July with 12, 11, and 8 yr. old kids. There's enough adults around, I'm not too worried about full pfd's because the kids are older, but they will have snorkel vests, with whistles (cheap from Amazon). I've witnessed both young and old, panic while swimming in deep water from the boat to some of the snorkel spots. I'm thankful my 12 yr. old started swimming lessons very young and could not care less about the water depth.

For the younger kids, I plan to use the dinghy with a rented boarding ladder, so I can ferry them back and forth over the deeper spots. Last thing I want is to have a guest get panicky far from the boat (again).

Finally, In my safety briefing (yep I actually do that with guests) we talk about a MOB situation, using the whistle, and the need to have one person keep their eyes on, and never take their eyes off, the MOB.

Have fun!