If you haven't taken your 2-5 year old to the Sea Squirts program at the Marine Discovery Center, located in New Smyrna Beach, I highly recommend you do. I used to take my kids there before the started elementary school. It's a great parent/child program where they learn about sea/nature themes. The cost of the program is $5 per person (and they do charge for the adult, which is the only bummer about the program).
Here's their upcoming schedule for this school year:
You will need to RSVP, by calling 386-428-4828. You can find more info here.