Tancheon (Korean: 탄천; lit. 'charcoal stream') is a stream in Gyeonggi Province and Seoul, South Korea. The stream is a tributary of the Han River. It begins in Yongin, Gyeonggi Province, flows through Seongnam, and eventually into the Han. It has a total length of 32.66 km (20.29 mi).

The area also serves as a large park, and there are paths for both walkers and cyclists on each bank with occasional foot bridges joining the two sides in addition to the bridges built for vehicle traffic. Along the paths there are many benches as well as exercise equipment. The whole area is extremely popular among local residents.

The original name for the stream may have been the native Korean word "Sutnae" (숯내; 순내; lit. 'charcoal stream'). The meaning of this name was translated into Hanja (Chinese characters) as 炭川; this can then be read in Korean as "Tan-cheon" (탄천).

The "Sut" or "Tan" part of the name may have come from a place called "Sut-gol" (숯골) or "Tan-gol" (탄골); this was an area along the river that corresponds to the current Taepyeong-dong, Sujin-dong, and Sinheung-dong in Seongnam. That area was considered to produce much charcoal.

The stream was officially assigned its name during the 1910–1945 Japanese colonial period.

The stream has been known by many other names, such as Geomcheon (검천; 儉川), Heomcheon (험천; 險川), Meonae (머내), Cheonhocheon (천호천; 穿呼川), and Jancheon (잔천; 鵲川).^{[citation needed]}

The stream originates from the mountain Beophwasan [ko] in Yongin. It flows north and merges with the stream Dongmakcheon in Gumi-dong. It then merges with the stream Jungcheon in Imae-dong, then with Yangjaecheon in Daechi-dong in Seoul. It then merges into the Han River near Seoul Olympic Stadium. It has a total length of 32.66 km (20.29 mi).

There are bicycle lanes and walking paths along the stream. Large apartment complexes line the stream. There is courts for sports such as tennis along the river.