Sierra Madre del Sur

The Sierra Madre del Sur is a coastal mountain range running along Mexico’s southern Pacific coast, primarily through the states of Guerrero and Oaxaca. It forms a rugged barrier between the Pacific coast and the interior highlands.

The range is characterised by steep, forested slopes, deep river valleys and a mix of tropical and montane ecosystems influenced by coastal climate patterns. It supports agriculture, forestry and a range of indigenous and rural communities adapted to mountainous terrain.

Over geological time the range formed through tectonic and uplift processes associated with the Pacific margin, generating complex topography and high biodiversity in isolated valleys. It remains an important source of rivers and ecological diversity for the region.

Geographically the Sierra Madre del Sur parallels the Pacific shoreline of southern Mexico and is a defining feature of the country’s southern landscape.

• Coastal position: The range stretches along Mexico's Pacific coast through Guerrero and Oaxaca and contains steep coastal slopes and river-cut valleys important for local climates and watersheds.
• Elevation range: Elevations vary widely but include peaks and ridges that can exceed 2,500-3,000 metres, producing montane ecosystems distinct from the lowlands.