I don't mean mine is the only choice. I just happened to be researching drive-to cruises and i was surprised by what I found.
So I was just making suggestions to avoid flying. I did research on how much it costs to fly a family of four and the savings of a drive-to cruise is substantial. Plus, Carnival pride is of the Spirit-class, one of the nicer Carnival ships. I just think it is worth a look.
Also - I stand by my recommendations for Kennedy Space Center and Atlantis. The amount of money you save by driving means you can afford day passes for the kids at Atlantis which has an amazing water park, probably the best in the world. And you can afford to go to Disney World for a day. That's pretty good fun for kids, too.
If you want snorkeling then go to the deeper Caribbean, but for kids, in fact, I think cruises to St Thomas, St Martin and a private island only offers swimming and not that much more.
The western caribbean will give you stingrays in Grand Cayman and zip-lining in Jamaica. Cozumel is good for snorkeling as well.