Puente del Inca

Useful Information

Location: Ruta Internacional n°7, near Puente del Inca, east of Las Cuevas, Mendoza Province.
Open: No restrictions.
Fee: free.
Classification: KarstNatural Bridge
Light: n/a
Dimension: L=28 m, W=47 m, A=2,717 m asl.
Guided tours:
Bibliography: Victor A. Ramos (2009): Darwin at Puente del Inca: Observations on the Formation of the Inca's Bridge and Mountain Building, Revista de la Asociación Geológica Argentina 64 (1):170- 179 (2009)
As far as we know this information was accurate when it was published (see years in brackets), but may have changed since then.
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1646 first written mention by Alonso de Ovalle.
1820 first description by Schmidtmeyer.
1826 description by John Miers.
04-APR-1835 visited by Charles Darwin.
1953 spa destroyed.
1984 Transandine Railway shut down.
2005 ruins closed due to the danger of collapse.


Puente del Inca (The Inca's Bridge) is a natural bridge at the Vacas River, a tributary of the Mendoza River. The bridge is extraordinary because it was actually formed by a hot springs. The hot water deposits huge amounts of minerals with a generally yellowish colour, which form huge lumps, plateaus and even stalactites. The bridge probably formed by the combination of ice and deposited minerals. During colder climate in the last cold age the river bed was filled with ice all year. The ice and the hot water were in a sort of equilibrium of melting and freezing, and while the surface of the ice stayed at a certain level above the river bed, the hot water deposited a crust of rock on top. Snow avalanches and and landslides deposited further material which was cemented by the minerals from the hot-water springs. This formed the bridge as a mineral deposit, so it is not of erosional origin as some webpages state.

The most famous visitor of the bridge was probably Charles Darwin, who visited Puente del Inca,during his second journey across the High Andes. He already realized the way it formed. He also found shallow water marine fossil mollusks intermingled with volcanic rocks. This led to new theories about mountain uplift, the subsidence of the marine bottom, the episodic lateral growth of the cordillera, and their association with earthquakes and volcanic activity. Although he was not impressed by the bridge, the influence of this location on the development of geology are of great importance.

The sulfuric spring is also named Puente del Inca, and was the reason for the construction of a big thermal resort and Spa in the early 20th century. The hotel was destroyed by an landslide or avalanche in 1953, and never rebuilt. There is now a spa further down the river at Cacheuta. The remains of the hotel offered a way to get under the bridge, but the building and the bridge were closed in 2005 due to the danger of collapse.

The Ferrocarril Trasandino (Transandine Railway) once ran along the river towards Chile. Here was the second last station in Argentina before it entered the 3.2 km long Cumbre Tunnel across the border. The guests of the spa arrived with the train. The nearby train station Puente del Inca was abandoned in 1984 and has been turned into a mountaineering museum. The Museo del Andinista was founded by a group of mountain climbers from Rosario province.