Embalse Ezequiel Ramos Mexía, commonly known as El Chocón, is a large artificial reservoir on the Limay River in the Patagonian region of Neuquén and Río Negro provinces, Argentina. The dam sits at approximately 381 metres above mean sea level, about 80 km upstream of the confluence of the Limay and Neuquén rivers. The reservoir covers a surface area of roughly 816 km² (83,000 hectares), with a maximum water depth of 60–64 metres and a total storage capacity of approximately 20,155 million m³, making it one of the largest artificial lakes in South America. The dam structure itself is 94 metres high and 2,500 metres long.

The reservoir impounds the waters of the Limay River, which originates at Lago Nahuel Huapi before eventually joining the Neuquén River to form the Río Negro. The surrounding landscape is characteristic of northwestern Patagonian steppe, and the viewpoint (Mirador del Embalse Ezequiel Ramos Mexía) near Villa El Chocón on Ruta Nacional 237 at km 1297 offers panoramic views across the reservoir. The town of Villa El Chocón, with a small resident population, serves as the primary base for visitors to the area.

Fishing is a popular activity on the reservoir. Regulations cover the stretch from Paraje Álamo Guacho to 500 metres before the El Chocón dam structure. The fishing season runs from November 1 through October 31 of the following year, with permitted species including trout, perca, and pejerrey. From May 2 onward, mandatory catch-and-release applies to all salmonids and barbless hooks are required. Pejerrey fishing is authorized through August 15 using specific equipment. The reservoir is classified as a free-fishing zone within these regulated parameters, and the water body is shared between Neuquén and Río Negro jurisdictions, so anglers should consult the Río Negro annex as well.

The reservoir is part of a broader hydroelectric complex that also includes the Arroyito plant 25 km downstream. Paddlers should be aware of the dam infrastructure at the southern end of the reservoir and the potential for regulated water releases, which can affect conditions on the water.