You can certainly bring your own snorkel gear. I doubt they're going to ask your ages when you head out. Make sure to also bring an inflatable snorkel vest as those are required in the snorkel area. One thing to note is that it's kind of haul to swim out to the areas with hidden Mickeys. After my ten year old got intimidated by the swimming distances, we spent the afternoon doing a lazy-man's snorkel in the swim area instead. We shared a raft and laid across it so it supported our bellies then floated around with our masks in the water. There were plenty of fish in the swim area out toward the lifeguard stand and it was actually less cloudy and crowded than on the "snorkel" side of the rope. We actually saw a barracuda! My daughter still talks about it, it was one of the highlights of her trip.