Starting from the northern regions of Chile, the finest cycling trails include Putre and Parinacota. However, they require cyclists to be in a good physical shape to tackle the high altitudes and unpredictable weather changes. Another amusing biking path lies through the Humberstone Saltpeter Works. A lot of cycling routes wind around the capital city of Santiago, particularly through the valleys in the countryside, the very city contains a nice biking route in the Parque Metropolitano. A great route also lies along the border between Chile and Argentina; one may even cross the boundaries and visit Argentina in the mountains and then come back to Chile. The best southern sites to explore by bike include the area around Lake Llanquihu and Petrohué Falls overlooked by snow-capped Osorno Volcano. Torres del Paine, as well as many other parts of Chilean Patagonia, are also accessible by bike. The season runs from September through May.