This isn't a forum for medical advice, of course, but I'd make the suggestion to heed the crew's statements if they say the ride on the Yankee Freedom out to Dry Tortugas National Park will be choppy. At the departure lounge they offer dramamine for sale, and quite a few lined up to buy it, but I decided I probably wouldn't need it and held on to mine. Bad call. The readily available seasick sacks got a good workout from me. The shipboard staff was very helpful, bringing ginger ale and more sacks, and I was far from the only one. I learned my lesson - took the pills before boarding for the trip home and all was well.