The Chao Phraya River is a major river in Thailand, originating from the Ping, Wang, Yom, and Nan rivers in the mountains of northern Thailand. It then flows south for 225 miles (365 km) to its mouth at the Gulf of Thailand. Bangkok, The Thai's past and present capital city, has been situated on the banks of the river or its tributaries and distributaries all through its history, as well as many other cities. Throughout the centuries, the people of Thailand have utilized the Chao Phraya for its many uses such as drainage, recreation, fishing, and as a source of water. Its waters provide a valuable transport system and its basin holds several major irrigation projects. Travelling from its headwaters to the sea, the Chao Phraya drops only 24 metres of elevation, making it a great spot for boating and swimming.