The major river of Thailand is the Chao Phraya. It has low alluvial soil which marks the plains of Thailand. Chao Phraya originates from the meeting point of two other rivers Ping and Nan. The main tributary to Nan River is the Yom River.

Wang River is another river which flows in northern Thailand and this is 335 miles long. It originates from Ping River.

The longest river in Thailand is the Chi River which is 765 km but the water flow is very low. It runs through the Yasothon province of Thailand.

Chao Phraya runs for 372 km from Bangkok to the Gulf of Thailand. It bifurcates into two in a place called Chainat. The main portion of the river, known as the Chin River, flows parallel to Chao Phraya and ends in the Gulf. It is called by many names. In Chainat, it is called Makhamthao river and when it passes through Suphanburi, it is called Suphan. It becomes Nakhon Chaisi river when it enters Nakhon Pathon and after that it is known as Tha Chin river when it reaches the mouth of Samut Sakhon. Many canals are diverted from Chin River and the water from the canals is used for irrigation.

Nonthaburi Uthai Thani, , Singburi, Nakhon Sawan, Ang Thong, Ayutthaya and Chainat Pathum Thani are the cities along the flowing river. Nakhon Sawan is the city where the two major rivers Nan and Ping meet. Ang Thong is an agricultural land and Chao Phraya and Noi River meet in this city.