No, its not necessary to snorkel only with going with a tour. I think I've mentioned before how to get over to St. Johns, from St. Thomas. Its very easy and the snorkeling and the whole island is wonderful, you can rent the equipment or take your own. Not too sure if you can rent a Kyak or not, but you can check around on the internet at those ports and see if its possible, but it may be a good idea to go with a tour, unless you're done that before at that certain port, don't want to get lost or hurt?? Our last trip to St. Thomas, we ended up going on the "wild thing" to snorkel and that was great fun too.
If there is some tour that you really want to do, be sure to sign up now to ensure that you can get it, great idea of Princess's to be able to pre-register for shore
excersions, have fun on Dawn, not long of a wait now!