Welcome aboard, Tanya! When you sail with Disney Cruise Line, there are so many activities and events included onboard and at Castaway Cay, you don't need to plan much extra onboard or on Disney's private island!
I'd encourage you to try out at least one of
Disney Cruise Line's Port Adventures in a different port of call though! They plan all the details and really make a magical day for families in port! However, if you want to skip a Port Adventure in
Cozumel, that's a great port to explore on your own! The ship pulls up to the dock in Cozumel and at the end of the dock is a huge shopping center, all within the port area! No need to venture out on your own out of the area, as you could spend the whole day browsing the stores and kiosks right there! Each time we've been there, there has also been an area through the upstairs shopping section, then downstairs where folks can get their photos taken with exotic local animals, like a money or a snake. (Personally, I opted for the monkey. I don't want a huge snake around my neck, thank you!) I believe it was either tip only or about $5 per photo taken with your own camera. That's an adventure in itself, believe me! My kids loved it!
When you're done exploring the huge shopping and dining area there in port, and ready to head back to the ship, there are bike-drawn buggies that take guests to and from the ship, down the very, very long dock area (a welcome treat when you see how long the walk is!). The last few times we've been there, there was no set charge, just tips. So, for a $5 tip, we hopped aboard, and the kids enjoyed a fun ride down the dock! They accept American dollars, so keep some singles with you for these types of things in Cozumel, and you'll be all set!
I hope that helps as you continue planning, Tanya! Have fun!
Marcy