Hundreds of species of marine animals lie just below the surface of the water. There are opportunities to view sharks, sea turtles, coral, lobsters, squid, octopus, tropical reef fishes, and Goliath groupers.

Dry Tortugas National Park, located 70 miles west of Key West, is a biological hotspot, primarily known for its spectacular marine and avian wildlife. The most famous residents are the Sooty Terns, as Bush Key is the only regular nesting site for this species in the entire United States. You can also spot Brown Boobies, Frigatebirds, and various migratory songbirds. Underwater, the coral reefs are home to Nurse Sharks, Goliath Groupers, and colorful Reef Fish like Parrotfish and Queen Angelfish. As the name "Tortugas" suggests, the park is a vital nesting ground for Sea Turtles, specifically the Green, Loggerhead, and occasionally the Hawksbill turtle. On the land surrounding Fort Jefferson, you might encounter the Mangrove Cuckoo or the occasional American Crocodile, which has been known to frequent the moat of the fort. In 2026, the park is a premier destination for "Eco-Tourists" and birders, offering a rare look at a nearly pristine Caribbean-style ecosystem that is strictly protected by federal law.