Ahoy, David!
Thanks for stopping by the Disney Parks Moms Panel with your question.
I'm happy to hear you're planning to enjoy the beautiful Snorkeling Lagoon when you visit Disney's private island,
Castaway Cay. My family has spent many hours exploring the lagoon, checking out the marine life and looking for hidden Mickeys! The lagoon has two different snorkeling trails to follow - the Discover Trail, for beginners, and the Explorer Trail, for snorkelers with a bit more experience.
Guests are more than welcome to visit Castaway Cay with their own snorkeling gear. Unfortunately, there is not an option to rent just fins on the island. If you're interested in renting fins, they are included in the
Snorkel Lagoon Equipment Rentals, along with masks and snorkels. For only a few dollars more, my family's favorite Port Adventure is the
Castaway Cay Getaway Package, a 3-in-1 package which includes snorkel equipment rental for the day, float rental for the day, and bicycle rental for an hour. We especially enjoy our time on the bikes, touring the island and working off some of those cruise calories!
The good news is that flippers are not required to participate in the snorkeling trails, so you can choose to bring your own mask and snorkel and go fin-less if you like. All guests are required to wear a life vest in the lagoon, and they are provided free of charge. They can be inflated to your comfort level, and are very lightweight and easy to wear to explore the Snorkeling Lagoon.
I hope this helps with your planning and preparations for your upcoming Disney Cruise Line vacation. Have a magical day! - Diane W.