El Paso de Agua Negra (Black Water Pass) is a high mountain pass, at an elevation of 4,780m above the sea level, located in the border between Argentina and Chile, linking the IV Region of Coquimbo (Chile) with the Province of San Juan (Argentina).
This infamous road is tightly hairpinned and bumped, an exquisite winding mountain drive with sharp and blind curves and hairpin switchbacks leading the traveler over the mountains. The road includes some steep sections, without market central lines, is very narrow, barely wide enough for 2 cars at the same time and it has not protections or guardrails. The surface of the road is gravel and sand, and chains or snow tyres can be required anytime.The pass connects La Serena and San José de Jachal. The distance between the major cities of both countries nearest to this pass is 505 km. 365 are paved and the rest are consolidated roads, but is driveable with any kind of vehicle.
Because of its altitude, this pass is open only in summer (from December to April). The rest of the year is blocked by snow. It is the highest border crossing between Argentina and Chile at an altitude of 4780 meters above sea level, and the traffic is low, being used by 200 vehicles every year.
Opened in 1965 , the road was closed in 1977 because political problems between the two countries and reopened to the public in 1994. Nowadays are being constructed 2 tunnels, with a total lenght of 14km, which will allow an inter-oceanic communication through this pass.
This is a maintained road where a high clearance 2WD vehicle is able to travel safely at low speeds on long dry straight-of-ways, without losing control due to wash boarding, ruts, or dips. All primitve dirt roads may be rocky with areas or soft gravel or sand that makes travel unsafe for sedans or RVs. Some road sections may require a high clearance 4WD vehicle, in four-wheel-drive, driven by a driver experienced in 4WD drive techniques to drive the road without getting stuck.