Private rental outfits include Boat Rental Plus, 2400 Collins Ave., Miami Beach (tel. 305/534-4307), where 50-horsepower 18-foot powerboats rent for some of the best prices on the beach. There's a 2-hour minimum and rates go from $99 to $449, including taxes and gas. They also have great specials on Sundays. A $250 cash or credit card deposit is required. Cruising is permitted only in and around Biscayne Bay. Ocean access is prohibited. Renters must be over 21. The rental office is at 23rd Street, on the inland waterway in Miami Beach. It's open daily from 10am to sunset. If you want a specific type of boat, call ahead to reserve. Otherwise, show up and take what's available.

Club Nautico of Coconut Grove, 2560 S. Bayshore Dr. (tel. 305/858-6258), rents high-quality powerboats for fishing, water-skiing, diving, and cruising in the bay or ocean. All boats are Coast Guard equipped, with VHF radios and safety gear. Rates range from $199 for 4 hours and $299 for 8 hours, to as much as $419 on weekends. Club Nautico is open daily from 9am to 5pm (weather permitting). Other locations include the Crandon Park Marina, 4000 Crandon Blvd., Key Biscayne (tel. 305/361-9217), with the same rates and hours as the Coconut Grove location; and the Miami Beach Marina, Pier E, 300 Alton Rd., South Beach (tel. 305/673-2502), where rates range from $229 for 4 hours and from $299 for 8 hours. Nautico on Miami Beach is open daily from 9am to 5pm. For money-saving coupons, log on to www.boatrent.com.