Known as a major river in Thailand, Chao Phraya is derived from the Thai word Menam which means river. The river begins at the confluence of the Ping and Nan River at Nakhon Sawan in the Nakhon Sawan province.

The river serves as the major transportation artery for a vast network of ferries and water taxis in Bangkok. The expanse of the river along with the land uponwhich falling rain drains into the bodies of water which form the Chao Phraya watershed. The Chao Phraya watershed is considered as the largest watershed in Thailand which covers 35% of the nation’s land and a draining with 157,924 square kilometers.
Its principal tributaries are the Pa Sak River, Sakae Krang River, Nan River, Ping River and the Tha Chin River. Every tributary is further tributed by additional minor tributaries which are usually referred to as khwae. Wang River enters the Ping River which is near Sam Ngao district in Tak province.