The river never turns brown and is always crystal clear, perennial and wild.
Silent Valley National Park is called Silent Valley because of a perceived absence of noisy Cicadas. It is locally known as ‘Sairandhrivanam’. It is located in the Kundali Hills, Palakkad district, Kerala, in the Western Ghats of South India. It is the core of the Nilgiri International Biosphere Reserve and is under consideration by UNESCO as part of The Western Ghats World Heritage Site.
The park is one of the last undisturbed tracts of South Western Ghats montane rain forests and tropical moist evergreen forest in India.
Silent Valley is rectangular, 7 km (east-west) X 12 km (north-south).