The Usambara Mountains are part of the Eastern Arc chain in the north-eastern part of the country. Their western and eastern ranges are divided by a 4 km wide valley of small villages and farms, and hiking trails cover the foothills and larger peaks. Day walks and overnight treks take visitors through some of the most concentrated areas of biodiversity in Africa. Bird watching is especially rewarding, and the views from the mountaintops stretch over the Masaai Steppe and, on a clear day, as far as the Indian Ocean.