Welcome aboard, Charles! Castaway Cay is one of my favorite beaches in the entire world! With so much offered for guests of Disney Cruise Line, it truly is a place where everyone can relax and unwind or go, go, go all day! It's up to you!
Both the
Seahorse Catamaran Snorkel Adventure and the
Rigid Hull Snorkeling Adventure are fabulous. The only real difference is the boat and the length of time you'll enjoy snorkeling. If cost is a factor, you'll still have a wonderful experience with the less expensive Catamaran adventure.
Keep in mind that back at Castaway Cay, snorkel rentals are available for guests to swim out on their own to explore Snorkel Lagoon where you'll see beautiful fish and some surprises that Disney has hidden under the sea in that area. My family enjoys snorkeling there and trying to find Mickey under the water! My kids love hunting for Hidden Mickeys on the ship and at Castaway Cay, so this is an extra special perk! You can certainly make advanced reservations for the
snorkel rental at Castaway Cay's Snorkel Lagoon, however, if you decide at the last minute to dive in, there are always plenty of snorkels and fins available to rent once you are on the island, so play it by ear and see how your day shapes up on the island.
Honestly, Charles, you can't go wrong with any of Disney's Port Adventures. Since you're strong swimmers, you'll get the most out of whichever snorkeling adventure you choose! Have fun planning!