A reason to visit the main island Bohol, is that Bohol still has tropical rainforests in the higher parts of the island. Moreover, If you want to meet the smallest monkey on earth, the Tarsier, you'll have to visit Bohol! The average size of this little creature is between 90 to 160 mm (3.5 to 6.25 inches). The weight is between 70 to 165 grams. Geologists think that the specific shape of the hills is caused by the influences of the weather during millions of years. The breaking down of the upper layers of the limestone formations, followed by the erosion processes, resulted in these remnants in the shape of cones. In the rainy season the Chocolate Hills are green. In the dry season of each year, the vegetation on the hills gives the landscape a brown colored view, a reason to call them "Chocolate Hills". One of the most spectacular landscapes in the Philippines is formed by the Chocolate Hills on the island Bohol. The Chocolate Hills have all the same shape, but differ in the altitude. The most of the 1268 hills reach 40 meters high.