Characteristic of this area is the dramatic contrast in topography. Mountain ranges, volcanoes, lakes, rivers and fertile plains support numerous varieties of bird and wildlife, each offering different types of activities. The two Cordilleras, or mountain ranges, are very different from each other. The Cordillera Tilarán has rolling mountains that used to be covered in cloud forests; those remaining are protected reserves of which the Monteverde Cloud Forest Biological Reserve is the most popular with visitors, offering nature trails, horse riding and canopy tours. The Cordillera de Guanacaste is an impressive string of volcanoes, some protected within national parks. Between the ranges are Lake Arenal and the nearby active Arenal Volcano and surrounding hot springs. Further north, in the tropical humidity of the lowland plains, lies the remote wildlife refuge of Caño Negro, a vast wetlands area that is one of the best places in the Americas to see river wildlife, including numerous birds, mammals and reptiles. The fertile plains are dotted with a mixture of agricultural fields, cattle ranches and expanses of protected areas serviced by a maze of streams and rivers.