Enjoyed our trip to the Dry Tortugas (Ft Jefferson) the last week of September '21. The sea was about 2' which made for a comfortable ride. The narrator Carrie kept us well informed though they could use a better speaker system since we couldn't hear everything she had to say. There was a few video screens around the ship to describe certain things pertinent to the trip, but the volume was too low to hear what was being said.
The lunch (a sub from Jersey Mikes with chips, cookies and a drink) was passed out once we reached the fort were fine. The bar was open on the vessel on the way back, which made for a nice end to a relaxing day.
On the island visitied the fort (no elevator), but a great view of the surrounding area and fort if you make it to the top. They have a guided tour, but we chose to self-explore. If you get too warm and need a break visit the fort's gift shop - it was delightfully air conditioned and cool. Then went snorkeling in one of the two areas designated for swimming. We brought our own gear, but the ship does have enough on hand out if you don't have your own gear. Saw a few jellyfish and some colorful fish and just relaxed on the beach.
The ship had fresh water wash down stations for your after-swim rinse off, but beware the water is warm (not hot) .
Bring a hat, sun screen and a towel.
You can also take a flight to Dry Tortugas, but the price is expensive. We preferred taking the Yankee Freedom because we weren't in a hurry (we planned to make a day of it), it was relaxing and we got to meet some interesting people.
I'd suggest you visit their website which has a lot of good information about the trip.
Smooth sailing, but don't forget to drop anchor and enjoy the sunset.