Dry Tortugas National Park, Florida

There’s no such thing as a quick jaunt to Dry Tortugas National Park; getting to the string of seven islands requires crossing 70 miles of open water via boat or seaplane from the Florida Keys. But this park’s remoteness is what makes it worth a visit (fun fact: Dry Tortugas is actually closer to the shores of Cuba than the American mainland). Sitting smack between the Gulf of Mexico and the Atlantic Ocean, the Dry Tortugas chain of keys served as an important navigational marker for overseas trade routes -- and it also served as the site of a lot of shipwrecks. Explore the sunken ships and coral reefs that sit just below the turquoise water via a snorkeling or diving expedition. See if you can spot colorful reef fish, nurse sharks, sea turtles, or -- gulp -- an endangered American crocodile. There are also great spots for fishing and kayaking throughout the park, just be sure to bring your own supplies and sea vessels since there are no rentals out here. And a trip to Dry Tortugas wouldn’t be complete without a tour of Fort Jefferson on Garden Key. Construction of the fort began in 1845 but was never really finished, though its moats and lighthouse make it an interesting visit today. Oh, and we should warn you: don’t plan on uploading any Instagram snaps while at this park -- cell service is practically nil. But hey, that’s just gives you more uninterrupted time to soak up the sun, sights, and history at this tropical outpost on the edge of America.