The Aquarium (right next door to the port) has luggage storage. Also, they will store your luggage in the port until 4:00 p.m. You could do that and wander around the port. There are shops, restaurants, movie theater, etc.. I always book a late flight out of Tampa. If there is any kind of weather you may not be able to get into the channel. Our last cruise out of Tampa we were supposed to dock at 8:00 a.m. but due to fog/weather we couldn't get into the channel. We didn't dock until around noon and then it was almost 2:00 p.m. before we cleared customs and were off the ship. Our flight wasn't until 4:00 p.m. so we were fine but a lot of people missed their flights and as it was a school vacation week a lot of them couldn't get flights out until two or three days later.