If you want to do more than weave in and out of the pedestrian obstacle course on South Beach -- a thrill in its own right -- Key Biscayne's Crandon Park Beach offers a chance to spread your skates. Children may do well to begin at the roller rink that's accessible from parking lots three and four. A nearby carousel offers a welcome diversion while a fountain with water-spewing sea horses is the perfect finish to a hot day's activities. Between the rink and the beach there is plenty of smooth pavement and shade. Coast along the pavement adjacent to the sea wall while you take in a soul-calming view of white sands, palm trees, and lulling ocean. Long-distance skaters seeking a breathtaking vista at a higher elevation may want to begin skating on Virginia Key. These explorers should take the Rickenbacker Causeway to the parking lot at Mast Academy Drive, then blade southeast over the bridge between the University of Miami Marine Lab and the Crandon Park Marina. From there you can enter a shaded park path or continue along the causeway's bike lane all the way into Key Biscayne village and Bill Baggs State Park. This circuit, from parking to Bill Baggs and back, is about twelve miles. Only the truly expert should try skating the bridge between the mainland and Virginia Key.