About 18km west of La Fortuna you’ll arrive at a 750m-long causeway across the dam that created Laguna de Arenal, the largest lake in the country at 88 sq km. Arenal and Tronadora were submerged during its 1979 creation, but the lake now supplies valuable water to Guanacaste, sport fish like rainbow bass, and hydroelectricity for the region. High winds also produce power with the aid of huge steel windmills, though windsurfers and kitesurfers frequently steal a breeze or two.
Circling the lake is one of the premier road trips in Costa Rica. The road is lined with odd and elegant businesses; strong winds and high elevations give the lake a temperate feel and the scenic views of lakeside forests and Volcán Arenal are about as romantic as they come.