Dry Tortugas National Park, Florida
Located about 68 miles west of Key West in the Gulf of Mexico, the Dry Tortugas National Park is easily one of the most underrated in the US. It is mostly composed of crystal clear waters and 7 small islands, with native sea turtles on every turn. The park is the ideal place to visit as a day trip that will be filled with lots of great snorkeling along the lively coral reefs. On top of that, you can also take a walk on a brick walkway around the island and learn plenty about its hidden history.