Wonchi lake is a picturesque crater lake which is located on the mountain range between the town of Ambo and Woliso. The lake is the beautiful legacy of a once powerful volcano erupting in the Tertiary period of the Cenozoic Era. The volcano erupted about 1000 years ago and left asymmetric caldera of rock which is now covered in lush green vegetation. The whole crater contains a large lake with small islands, hot mineral springs, waterfalls and beautiful valleys and farmland.