Volcán Arenal National Park

Costa Rica's largest inland body of water, shimmering Lake Arenal, all 125 square km (48 square mi) of it, lies between rolling green hills and a rumbling volcano. Many visitors are surprised to learn it's a man-made lake, created in 1973 when a giant dam was built. A natural depression was flooded, and a 32-km-long by 14.4-km-wide (20-mi-long by 9-mi-wide) lake was born. The almost constant winds from the Caribbean make this area a windsurfing mecca. Outfitters in La Fortuna, Nuevo Arenal, and Tilarán run fishing, windsurfing, and kitesurfing trips on the lake. Desafío, an operator based in La Fortuna and Monteverde, has a half-day horseback trip between the two towns, with great views of the lake.