did this in March. Great snorkeling for me, my Husband and 10 year old. I also have a 6 year old. We left her with my parents because we were worried she wasn’t a strong enough swimmer yet. It was the right decision for her. Open water and choppy would have been above her level. It’s around an hour in the water at least. We stayed in the whole time because it was great seeing the reef. But there isn’t anything else to do but sit on the boat if the little ones can’t do it or tire out. They do have inflatable vests to assist with floating. Some adults (including me) were wearing these just to avoid tiring out and enjoy the reef more. Hope that helps.
Edited to add: it’s about 30 feet deep and out from shore so there’s not a place where you can stand.