Sicily's greatest natural attraction is the (very) active volcano, Mount Etna, which has been spewing lava and shaking the earth for centuries, most recently in 2008, while ash eruptions occur almost continuously. About 20 miles (32km) from Catania, the craters below the summit can be reached from the town of Piano Provenzana at the base by mountain bus or on foot. This town also serves as a ski resort in winter, and during summer is a base camp for hikers intent on enjoying the wooded scenery and exploring the interesting caverns in the area. Various species of oak and stone pine, birch and beech trees cover the lower mountain slopes, while frogs, toads, tortoises and Sicily's ubiquitous lizards hide in the forest streams. Foxes, weasels, squirrels and other small mammals stalk the forests and a plethora of bird species fill the trees and the Gurrida Lake area. The lovely flora and fauna are an extra bonus for hikers exploring the area, and the volcanic activity attracts photographers. Mount Etna features rather prominently in Greek mythology and has been captivating people for centuries; it is one of Italy's most famous natural features and a playground for adventurers of various kinds.