I am a serious National Park lover and absolutely loved Dry Tortugas/Fort Jefferson National Park! We took the Key West Seaplane Adventure's seaplane over (AMAZING experience, and described on their attraction's review), and spent two-plus hours at the park. The first 45 minutes of our time was spent walking around, taking tons of pictures and taking in the beautiful sights of Fort Jefferson. I love that the fort is in an 'original state' and that we have the freedom to walk around the three levels of the brick fort, and also along the moat wall surrounding it. The views are beautiful -- I especially enjoyed the panoramic sight from the top of the fort of the interior courtyard and then out to the various shades of incredible blue of the Caribbean surrounding the island. I also marveled at the long hallway of skinny arches located on level two --- be sure not to miss it; wonderful picture opportunity! :)
The entrance fee to the park is extremely low ($5). The self-guided tour shows off all of the features and must-sees of the fort perfectly. Depending upon the year it can be super hot, so be sure to take a hat/sunscreen/sun-protection. I had a SPF surf shirt that I was using for snorkeling and it was perfect for sun protection while walking around the fort.
There is only one entrance into the fort, and the visitor's center/gift shop/exhibits are located directly on the right once you cross the bridge over the moat and walk into the fort. The gift shop and interior exhibits of military artifacts and equipment are very good and interesting --- and also air-conditioned :)
The snorkeling is fantastic! Lots of beautiful coral, sea fans and fish are found in and around the coaling dock remains. A fantastic experience is being able to snorkel IN and AMONG them! (Just be careful with where you hands and feet are in regard to the fragile coral!) A certain part of the sea surrounding the island you can't snorkel in, but from the south coaling area all the way 'around' (the long way around the island) the fort to the north coaling area is all open for snorkeling.
Additional important information: there is no food or water available on the island so be sure to bring your own! When the ferry is docked outside the fort, it's facilities (restrooms, fresh-water showers) are available to everyone in the park. When the ferry is not docked, there are composting toilets available near the beach outside the entrance of the fort. The structure directly in front of the entrance contains changing rooms as well as a room with a guestbook for signing and informational brochures for the park.
Enjoy this beautiful and secluded park --- you won't regret it! :)
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.