Nan River

Nan River
Nan River at Wat Tha Luang, Phichit Province
Country	Thailand
Tributaries
- left	Wa River, Pat River, Khwae Noi River, Wang Thong River
- right	Yom River
Cities	Nan, Uttaradit, Phitsanulok, Phichit, Nakhon Sawan
Source
- location	Luang Prabang Range, Bo Kluea District, Nan Province
- elevation	1,240 m (4,068 ft)
- coordinates	19°20′0″N 101°12′0″E / 19.33333°N 101.20000°E / 19.33333; 101.20000
Mouth	Confluence with Ping River
- location	Pak Nam Pho, Nakhon Sawan Province
- elevation	25 m (82 ft)
Length	740 km (460 mi)
Basin	57,947 km2 (22,373 sq mi)
Discharge	for Nakhon Sawan
- average	472 m3/s (16,669 cu ft/s)
- max	1,522 m3/s (53,749 cu ft/s)
Map of the Chao Phraya River drainage basin showing the Nan River

The Nan River (Thai: แม่น้ำน่าน, rtgs: Maenam Nan, IPA: [mɛ̂ːnáːm nâːn]) is a river in Thailand. It is one of the most important tributaries of the Chao Phraya River.

The Nan River originates in the Luang Prabang Range, Nan Province. The provinces along the river after Nan Province are Uttaradit, Phitsanulok and Phichit. The Yom River joins the Nan River at Chum Saeng District, Nakhon Sawan Province. When the Nan river joins together with the Ping River at Pak Nam Pho within the town Nakhon Sawan it becomes the Chao Phraya River. The Nan river runs about 630 kilometres (390 mi) south.

The chief tributary of the Nan is the Yom River, which joins the Nan within Chum Saeng District in Nakhon Sawan Province. Other direct tributaries include the Butsabong and Wang Pong rivers of the lower Nan Basin, the Wat Ta Yom and Wang Thong Rivers which join the Nan within Phichit Province, the Khwae Noi River which joins the Nan within Phitsanulok Province, the Tron and Pat Rivers, which join the Nan within Uttaradit Province, the Wa, Haet, Pua, Yao and Hao Rivers, which join the Nan within Nan Province.