Tiasmyn River

Infobox River
river_name = Tyasmyn, Тясмин

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caption = A bridge over the Tyasmyn River in Cherkasy.
origin = Kirovohrad Oblast, Ukraine
mouth = Kremenchuk Reservoir, Dnieper River
basin_countries = Ukraine
length = 164 km
elevation =
discharge =
watershed = 4,570 km²

The Tyasmyn ( _uk. Тясмин) is a river, a right tributary of the Dnieper River, in Ukraine. The Tyasmyn takes its source in the north central part of the Dnieper hills in the central Ukrainian province of Kirovohrad. From there it flows through the Cherkasy Oblast, where it finally flows into the Kremenchuk Reservoir. The river forms a u-turn "(180°)" in its central run. Not counting the river's sharp turn, the river delta, and the river's source "(from snow thaw)" are located only 33 km away from each other.

In the river's lower flow, there are important discovery sites of the "Belogrudovka/Cernoles Culture" in proximity of the settlement of Subotiv. These findings represent a key place for the late Bronze Age.

Cities and towns located on the river include: Kamyanka, Smila, and Chyhyryn.