Arroyo Ñacanguazú is a watercourse in the province of Misiones, Argentina, part of the broader Cuenca del Plata drainage system. It originates in the Sierra de Misiones and flows through the municipalities of Santo Pipó and Jardín América, both within the Departamento San Ignacio, before emptying into the río Paraná. The stream's total length, including its tributaries, reaches 42.3 kilometers, and its watershed covers an area of 354 square kilometers. The mouth of the arroyo is located at approximately 27°05′35″S, 55°26′38″W.

The most notable feature along the arroyo is the Salto Ñacanguazú, a waterfall with a drop of approximately 10 meters situated near Santo Pipó. This feature represents a significant hazard for paddlers and requires a portage. The arroyo is crossed by a bridge on Ruta Nacional 12 near Santo Pipó, which provides a reference point for access.

Paddlers considering a trip on the Ñacanguazú should conduct thorough on-the-ground research, particularly regarding the Salto Ñacanguazú and any other drops or obstacles along the course. Flow can be affected by rainfall variability in the region, and conditions should be assessed before paddling.