| Untxin | |
| Pushpin Map: | France#France Nouvelle-Aquitaine |
| Source1 Location: | Xoldokogaina |
| Source1 Coordinates: | 43.3278°N -1.7158°W |
| Mouth Coordinates: | 43.3914°N -1.6836°W |
| Subdivision Type1: | Country |
| Length: | 9.50NaN0 |
The Untxin is a coastal river of the French Basque Country, in Nouvelle-Aquitaine, Southwest France. It is 9.5km (05.9miles) long.
It rises on the northern slope of the Xoldokogaina, elevation 479m (1,572feet), in the east of Biriatou.The motorway of the Basque Coast (A63) is settled in its valley. It collects in Urrugne waters from the Mandale. The Untxin flows into the ocean in Ciboure.