| Oso | |
| Pushpin Map: | Corsica#France |
| Subdivision Type1: | Country |
| Subdivision Name1: | France |
| Subdivision Type2: | Region |
| Subdivision Name2: | Corsica |
| Subdivision Type3: | Department |
| Subdivision Name3: | Corse-du-Sud |
| Mouth: | Tyrrhenian Sea |
The Oso (or Osu) is a small coastal river in the southeast of the department of Corse-du-Sud, Corsica, France.
The Oso is long.It crosses the communes of Lecci, Porto-Vecchio, San-Gavino-di-Carbini and Zonza.The Oso rises to the southwest of the Monte Calva.The source is in the territorial forest of L'Ospedale at an altitude of about northeast of the Punta di u Diamante.
In its upper section the stream is called the Ruisseau de Piscia di Ghjaddu.A waterfall on this section is one of the regional tourist attractions.It flows southwest, then southeast, and receives the Ruisseau de Palavesani from the right, which drains the Ospedale Reservoir.It then flows east and then south, then turns west to enter Stagnolu Bay to the west of Saint-Cyprien.There are beautiful natural pools for swimming in the mountainous section and in the plains.
Measurements of the river flow were taken at the Lecci station from 1968 to 1980.The watershed above this station covers .Annual precipitation was calculated as .The average flow of water throughout the year was .
The following streams (ruisseaux) are tributaries of the Oso (ordered by length) and sub-tributaries: