What National Park in Florida is underwater?

Biscayne National Park is home to 173,000 acres of land, most of which are underwater, and also features the longest mangrove forest in eastern Florida.



Biscayne National Park, located just south of Miami, is unique because 95% of its 172,000 acres are underwater. It is a "High-Fidelity" aquatic wonderland that protects four distinct ecosystems: a shoreline mangrove forest, the shallow waters of Biscayne Bay, the northernmost Florida Keys, and a vast section of the third-largest offshore reef in the world. Visitors to this park primarily explore by boat, as the "High-Fidelity" highlights include the Maritime Heritage Trail, which features several shipwrecks accessible to snorkelers and divers. Another high-fidelity Florida park with significant underwater components is Dry Tortugas National Park, famous for Fort Jefferson and its pristine coral reefs. For 2026 travelers, Biscayne is a high-value necessity for experiencing the fragile beauty of seagrass beds and tropical fish populations that thrive just miles away from the vibrant Miami skyline.

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Biscayne National Park is 95% underwater and 100% worth preserving, protecting and restoring.

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But a national park that's 99 percent underwater, located 70 miles from civilization, and accessible only by seaplane or boat? That's a next-level national park. Enter Dry Tortugas National Park, one of just three designated national parks in Florida — and one of the most remote in the entire U.S. National Park System.

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Located in the southwest corner of the Florida Keys reef system, Dry Tortugas National Park is a remote park that is more than 99% water. Its crystal clear ocean waters abound with incredible marine life.

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Located some 70 miles west of Key West, and consisting of wide-open water and a smattering of small islands, Dry Tortugas is actually the wettest national park in the country—one that necessitates swimming and snorkeling to really grasp its breadth.

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Dive Bahrain, the world's largest underwater theme park spanning an area of 100,000 square metres – complete with a sunken Boeing 747 – is now open to diving enthusiasts.

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You said Everglades National Park, right? You probably didn't say Timucuan Ecological and Historic Preserve or De Soto National Memorial. And therein lies a great opportunity, because there are 11 national parks in Florida, several of which are little known hidden treasures.

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Based on compliant water sampling results, all waters surrounding Virginia Key and Key Biscayne – except for Crandon Beach North and South are no longer under the no-swim advisory. The Marine Stadium Marina is also still under the no-swim advisory.

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The Port of Miami Tunnel (also State Road 887) is a 4,200-foot (1,300 m) bored, undersea tunnel in Miami, Florida. It consists of two parallel tunnels (one in each direction) that travel beneath Biscayne Bay, connecting the MacArthur Causeway on Watson Island with PortMiami on Dodge Island.

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Originally named the Atlantis Memorial Reef, the lost city is part of an underwater cemetery that also acts as an artificial reef, sponsored by the Neptune Society, a cremation company.

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Although the only cities currently underwater are those that were submerged over time, plans for underwater cities of the future are already being considered. These plans are not as far-fetched as they sound, and some underwater restaurants and resorts already exist around the world.

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National Park of American Samoa: The least-visited US national park in 2022 saw just 1,887 visits. Most visitors will need a passport to travel to American Samoa. 2. Gates of the Arctic National Park and Preserve, Alaska: This vast park contains no roads or trails.

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Are there sharks in Dry Tortugas? Yes, there are sharks in Dry Tortugas National Park. The most common type of shark seen in the park is the nurse shark. Nurse sharks are not aggressive and are sometimes called the “couch potato” of the shark world.

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Overnight anchoring is allowed in the area of sand and rubble bottom within 1 nautical mile of the Fort Jefferson harbor light and must not block any designated channel. Overnight anchoring is not permitted at any other location in Dry Tortugas National Park.

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