These are frequently searched on my blog. I wanted to answer your questions!
Mooring IS permitted in St. John anywhere you see a spot you can take it and hook up to your very own beautiful white mooring ball. Your boat must not reach 55ft. long, and not permitted to anchor wherever you see the swimming dinghies. Cost is $15/ day, $10 if you decide to anchor. You are only permitted to anchor/moor for 14 days total that is it. No longer. Pay stations are located all over the island. Contact the National Park Office for more specific details for your boating adventure and for the Pay Station locations.
Another searched a lot on my blog. The beaches. They are all free in the park except Trunk Bay. Trunk Bay is $4 for admission. Snorkeling is free and permitted at all beaches. You do not have to pay additionally for Trunk Bay for the snorkeling trail. It’s just the cost of admission. NO Jet Skis are permitted, ever.
Please as I say this constantly. Be aware of your surroundings at all times upon snorkeling. Watch your flippers from the coral. Do not touch the fish. WATCH THE TIDE. Yes, the water may appear calm, but when you venture further out it gets very strong. Be very careful. I was almost screaming for help at Hawksnest Beach because the current took me out a bit and was becoming very strong and I am a strong swimmer. I swam parallel to shore and gave it my might to get back safely. There are no lifeguards on the majority of all beaches. Please use caution and common sense.