The Arroyo Sauce Grande is a tributary of the Río Sauce Grande in Buenos Aires Province, Argentina. The Río Sauce Grande system originates at approximately 500 meters above sea level in the Ventania mountain range, draining the sierras of Curá Malal, Ventana, and De Las Tunas, before flowing through Villa Arcadia and Saldungaray and eventually reaching the coast near Monte Hermoso. At least one documented kayak trip of 8 kilometers has been completed on the river in this region.

The lower course of the system drains into Laguna Sauce Grande at roughly 8 meters above sea level, before the water reaches the Atlantic Ocean near Monte Hermoso. The laguna has an original basin of approximately 5,000 hectares, an average depth of 1.60 meters, and a maximum depth of just over 4 meters. Its waters are clear and greenish. The laguna is a fiscal property open to the public daily from 7:00 to 21:00, with navigation permitted until 19:00. Entry fees apply for vessels, including separate charges for motorized boats, sailcraft, and personal watercraft.

The mouth of the Río Sauce Grande, located about 17 kilometers from the center of Monte Hermoso, is accessible only by 4x4 vehicles or vehicles suitable for beach driving. This area supports notable wildlife, including zorros pampeanos, carpinchos, nutrias, and a wide variety of bird species such as flamencos, garzas, ostreros, patos, gaviotines, and gallaretas, making it of interest to paddlers who also value wildlife observation.

The upper stretches of the river system hold pejerrey and rainbow trout, the latter being unusual for Buenos Aires Province. Anglers frequently use the waterway, which may be relevant for paddlers planning routes through fishing areas.