The Río Cruz del Eje is formed by the confluence of the ríos San Marcos, Quilpo, and Candelaria in the northwestern corner of Córdoba province, Argentina, roughly 144 km from the provincial capital. From its headwaters it drains a basin of approximately 1,700 km² and runs a total length of around 200 km before terminating in the Salinas Grandes, an endorheic depression with no outlet to the sea. Mean flow is recorded at 3 m³/s, reflecting the semi-arid character of the region — a transitional zone between the Sierras de Córdoba and the desert lowlands.

The dominant feature on the river is the Dique Cruz del Eje, an impoundment completed in 1943 and substantially remodeled in 1980. Its dam wall extends 3,080 m, making it one of the longest in South America, and the reservoir holds 112 Hm³ at spillway level. The embalse is located approximately 7–8 km south of the city of Cruz del Eje and is accessible via Ruta Nacional 38 and provincial route A185. The reservoir is explicitly promoted for kayak and windsurf activities, and boat rental clubs operate in the area. The broad, open water surface and the backdrop of the sierras define the paddling environment on the embalse.

Downstream of the dam, the Río Cruz del Eje passes through the urban area of Cruz del Eje, where the riverbanks have been developed with balnearios — sandy beach areas with facilities for day use, including asadores (grills) — making this stretch a popular recreational corridor, particularly in summer. The river in this section runs to the right of Avenida Arturo Illia heading south from the city center, with several clubs and recreational spaces along the way.

Fish species present in the reservoir include pejerrey, carpa, tararira, dientudo, and dorado. The region is characterized by a dry climate with approximately 300 clear days per year, which has practical implications for paddlers regarding sun exposure and wind conditions on the open reservoir.