Pedaling is easy on pancake-flat beaches, but there are also some steep hills in the D.R. Several resorts rent bikes to guests and nonguests alike. Iguana Mama (Calle Principal 74, Cabarete. 809/571-0908 or 809/571-0228. www.iguanamama.com) has traditional and mountain bikes and will take you on guided rides on the flats or test your mettle on the steep grades in the mountains. Downhill rides, which include a taxi up to the foothills, breakfast, and lunch, cost $85 for a full-day trip, $60 for a half-day trip. Advanced rides, on and off roads, are $40 to $50. Guided hikes cost $35 to $65.