Not Clearwater. Key West, Jacksonville, maybe Pensacola.
We didn't get to any of those locations when I was a kid.
On the trip with the submarine, it was in a small park beside the hotel.
We were in Fort Lauderdale at a hotel/golf resort for my dad"s sales conference, then stayed in a cheapo Howard Johnson's beside Disney, and then went to Tampa, Clearwater, St. Pete. an eventually flew home from there.
I had to be in the Tampa St Pete region.
I remember walking outside the hotel on my own to explore. The weather after we left Disney, was really cold for the locals, but for a prairie kid who just came from -30C it was still heaven because I could wear a fall jacket in mid winter
I walked outside to explore and was amazed to find the sub in the park next door.
Alas it was closed to tours. Likely due to the wimpy locals
Edit: may have been the USS Requin SS481.. in Tampa. I just found a photo on a Florida historical site. Apparently the boat was there until 1986 when it ran out of money.