For the novice runner, a lap around the cool, milelong, tropical hardwood hammock trail sure beats going the distance on the beach. The sun won't pound on your neck while you search for the ever-elusive stretch of firm sand. And you won't have to avoid sunbathers or jellyfish. For the marathoner it's a place to loosen up and take in the surroundings before heading out for the nearby causeway. And while burning off your breakfast, you might see a soft-shell turtle plop into Arch Creek or spot songbirds in the shrubs near the bank. Or maybe you'll catch a heron pacing through the mangroves or an anhinga perched on a branch. Just make sure that while you're negotiating the sabal palms, firebush, and milkweeds, you don't trip and fall. That could hurt.