This was an awesome experience. We went in February during an unusually warm day (80 degrees). It was nice, not too humid or buggy. If you're not used to southern humidity and bugs, I'd plan to visit here during winter or late fall months. The visitor's center was great. The staff were helpful and shared so much information. It's such a neat experience. The boat tour is an additional cost, and it is totally worthwhile.
There is a federal park fee cash or card are accepted.