The highlight of my trip to Florida was swimming with manatees at crystal river. It's a crazy thought to be swimming and interacting with wild animals that are more than twice your size, but I would definitely recommend it if you are like me and have exhausted your fair share of Orlando theme parks.
There are quite a few companies in the area that allow you to swim with manatees. My sister had a groupon with the American Pro Diving Center. You basically go to the shop, fill out out some forms, rent gear, and watch a short video on manatee conservation. The dive master will meet you on the pier where they take you by boat to wherever they see manatees. It's then a two hour swim with these animals where you can watch them and touch them if you want. When you first get there everyone is really excited to have found them so you all fight for a spot around a single manatee or pair of manatees. The best part, in my opinion, is towards the end when everyone has gotten a chance to interact with them and you can find a manatee on your own and just swim with it without worrying about other people. It was a really peaceful experience and I am 100% glad that I went.