There is a trail that runs along the rivers and down the folds of the mountains from Monteverde, Costa Rica and into the Poco Sol Biological Station; somewhere in the middle lies a little valley called Peñas Blancas. Here, you can walk along the riverbeds and find mushrooms growing on the undersides of logs, and eyelash vipers sunning themselves on the moist and mossy rocks that sit along the banks of the running water. Peñas Blancas lies within the boundaries of the Children's Eternal Rainforest, Costa Rica's largest private reserve of primary and secondary forest. Now thirty years old, the story of the reserve began when a group of Swedish schoolchildren visited Monteverde, and returned home with a determination to preserve the forests that they had seen from the chainsaws humming in the distance; their ambition snowballed, and soon the Monteverde Conservation League was receiving donations from all around the globe. Because of these efforts thirty years ago, the vital, earth-supporting biodiversity that resides in these mountains thrives; old pastureland regenerates into forest; and the watershed that quenches the thirst of the Central Valley flows pure. And most importantly, eyelash vipers sit on rocks in the warm beams of sun beside the singing river.