Embalse El Tunal, also known as Dique El Tunal, is a reservoir located in the Departamento Metán of Salta province in northern Argentina. It sits 184 km from the city of Salta and approximately 80 km from the town of Metán, accessible via Ruta Nacional 16, roughly 6 km west of the Estación El Tunal of the Ferrocarril General Belgrano. The reservoir was inaugurated on April 15, 1972, and its dam is officially named Presa Gral. Martín Miguel de Güemes. The dam stands 41 meters in height. The reservoir's primary functions are hydroelectric power generation and seasonal water regulation, compensating flows from the Embalse de Cabra Corral along the Río Juramento, located 120 km upstream. It feeds irrigation for approximately 62,000 hectares in Salta province and 48,300 hectares in Santiago del Estero province.

The surrounding landscape is characterized by dense subtropical vegetation typical of the monte chaqueño, giving the water a wild, rugged setting. The reservoir is fed by the Río Pasaje, Río Juramento, and Río Salado.

Nautical sports are permitted on the reservoir, and basic facilities for overnight stays and camping are available on site. Fishing is a popular activity, with notable species including dorado, tararira, sábalo, bagre, boga, and pejerrey. However, paddlers and visitors should be aware of specific fishing regulations: fishing is only permitted from the shore and is prohibited from any watercraft. Retaining or killing dorado is also prohibited. The Secretaría de Medio Ambiente of Salta province maintains regular enforcement presence at the site. The reservoir is subject to poaching pressure, which has contributed to variability in fish populations.

The reservoir's coordinates are approximately 25°13′39″S, 64°28′37″W. The water body is owned and operated by AES Corporation as part of the national interconnected power system. Paddlers considering a visit should factor in the remote location and the basic nature of the available facilities, as well as the subtropical climate of the region when planning their trip.