The coral forms a kind of underwater condominium which also is home to crabs, sea urchins, snails, lobsters, shrimps, worms, chitons (mollusks), starfishes, sea cucumbers, sand dollars, barnacles and sponges. These are the life forms of another world. And a visit to this alien place is very much like traveling through space to another planet. For close observation, one needs a "spacesuit" - in this case, a tank - filled with compressed air, and regulator, a face mask, fins and snorkel. A glass-bottomed boat acts as a kind of spaceship for those who don't want to take an actual plunge

There are four basic ways to visit Pennekamp's residents: Glass-Bottomed Boats; Scuba Dive; Snorkeling; and Sailing. There are more than 30 independently owned dive shops in the Key Largo area which offer similar diving and snorkeling trips. Divers and snorkelers who want to see something man-made in this underwater world besides wrecks can go to Key Largo Dry Rocks, where there is a nine-foot bronze statue of Jesus Christ in about 20 feet of water. There also are large brain, stag and elkhorn coral formations and a four foot barracuda who likes to be photographed.

Inevitably, there are one or more people in most family groups who couldn't care less about the park's underwater inhabitants. For them, there are two manmade beaches, as well as canoe, kayak, and sail boat rentals and nature trails.