(AP) — The Overseas Highway links Florida's mainland with Key West, and some tourists drive straight through the chain without exploring until they get to the end of the road. Located only 65 miles (104 km) south of Miami on the island of Key Largo, John Pennekamp Coral Reef State Park is a good first stop on a road trip to Key West. Extending 3 miles (4.8 km) into the Atlantic Ocean, the park encompasses about 235 square miles (608 square km) of seafloor that includes the only living coral reef in the continental United States and seagrass. Privately owned boats ferrying divers and snorkelers often hover over the reef, but the park and private vendors offer reasonably priced day trips for tourists. Brightly colored tropical species like parrotfish and angelfish dart past waving fan coral, along with the occasional barracuda and stingrays. Mobile homes painted all sorts of tropical shades line narrow streets in the upper keys, and residents go out of their way to give them an island feel. Many of those same neighborhoods are built around narrow canals that were dug of the coral bedrock decades ago to provide easier access to the sea. Look down into the water and you're likely to see a manatee, the endangered "sea cows" that live in backwaters around the Keys. Thousands of anglers visit the Florida Keys each year hoping to catch tarpon, a mammoth species of silver-and-green fish that often grows larger than 150 pounds.