Sierra de la Ventana

The Ventania system rises abruptly from the flat pampas of southern Buenos Aires province, a range of folded quartzite hills reaching around 1,240 metres at Cerro Tres Picos, far older than the Andes and utterly unlike the surrounding plain. Its emblem is the Cerro de la Ventana, where erosion has worn a hole clean through a rock wall near the summit, a window some eight metres across that can be reached on a demanding half-day climb from the Tornquist provincial park. Other routes lead to Cerro Bahía Blanca for shorter walks, and to the Garganta del Diablo and Piletones stream pools. Two villages, Sierra de la Ventana and Villa Ventana, serve as bases with hotels, cabins and restaurants.

What you actually see

• The window - the natural hole through the rock near the summit of Cerro Ventana.
• The quartzite ridges - ancient folded hills rising straight from the pampas.
• The stream pools - Piletones and Garganta del Diablo swimming spots.
• The base villages - Sierra de la Ventana and Villa Ventana with lodging.

When to go

March to November for walking; summer is hot on exposed rock and trails may close on high-risk fire days. The window climb is registered at the park and has cut-off times for starting. Winter mornings can be frosty but clear.

Honest expectations

The climb to the window is steep, exposed and takes around five hours return, harder than its modest altitude suggests. Access is controlled with entry times and quotas. Water must be carried, and afternoon storms build quickly in summer.

Nearby

Bahía Blanca lies south; Tornquist and the provincial park are between the villages.