The Dry Tortugas are about 75 miles from Key West, so getting there involves a boat or seaplane trip. We went on the M/V Spree, a 100-foot boat that mostly does diving tours. Our group of 24 birders (two guides and 22 customers) spent four nights on the Spree, starting out the first night at the dock (sailing around 3AM), two nights moored at the Dry Tortugas, and the final night back at the dock after our late arrival. It was about a seven-hour ride between Key West and the Dry Tortugas.
The Dry Tortugas are several small islands. The largest island, Garden Key, is entirely occupied by Fort Jefferson, one of the largest forts ever built. It was under construction from 1846 to 1875 and finally abandoned without ever being completed.
Docking is very limited at Fort Jefferson, so we stayed moored offshore and commuted by inflatable boat.
Like I said, the fort occupies an entire island. It also has a moat.
The moat has a crocodile.
We looked for the crocodile but couldn't find it.
Lots of migrating birds fly across the Gulf of Mexico, and by the time they get this far on their trip north they are desperate to find any land. The parade grounds inside the fort are very welcoming to birds and a great birding spot during migration.
We didn't see any seaplanes, but day-trippers and campers can come over on the fast Yankee Freedom III, which can make the trip in only 2 hours 15 minutes.