One small stop we did while driving through the Florida Panhandle was the Falling Waters State Park. It was an excellent stop and very cheap to get in. It wasn't far from I10 either. It is home to the state of Florida's largest waterfall which happens to fall into a giant sinkhole. There is a boardwalk toe explore the property and go down to take pictures of the waterfall itself. We really enjoyed this little top and highly recommend it especially given the price and the proximity to the interstate. There are are other things like sinkholes to see besides the main waterfall too.