John Pennekamp Coral Reef State Park was the firt underwater state park in the country, and it's famous amongst snorkelers and scuba divers. The waters of Key Largo a especially clear, and there are frequent snorkel & dive excursions out of the Park. Even if you don't intend to pursue these activities, there's plenty to do on land, too. There is a wonderful nature trail that meanders through some pretty thick mangroves, and then along a canal that eventually leads out to the ocean. From the bridge along the water, wave to kayakers setting out or coming in from their excursions. Above the wooden planks that serve as boardwalk access over the mangrove roots, there's also an observation tower, from which you can see over the tops of the mangroves. There are guided walks, or just meander around by yourself and read the instructive signs placed along the trail. There are campfire programs, canoe trips, picnic area, and of course camping. Lots of restrooms, a marine store, a snack bar, and showers make this park not only beautiful and fun but also convenient and pleasant. There's a small admission fee, and i'ts open 8am to sunset.