It was raining for most of the morning so I didn't get into town until 11:00. First I went south of town about 10 miles to Fort Matanzas which included a short boat ride on a big pontoon boat over to the fort itself. On the way back we saw some dolphins about 100 yards away.
Back in town I parked downtown and walked for the rest of the day. First I went to the Ripley's Believe it or Not! Museum. There were a lot of dumb African skulls and skin and carvings that I didn't really care for but a ~20 foot tall Ferris wheel built using Erector set pieces was among the things I did like.
Then I went over to Castillo de San Marco and walked around the outside of that but didn't go inside because it was about to close. I ate and then walked around town for a while, including across the lifting bridge from which I could get a good look at big boats in the marina.