Tonlé Sap (ទន្លេសាប), the largest freshwater lake in Southeast Asia, is a vital ecological and economic hub in Cambodia. Known as the “Great Lake,” it expands dramatically during the monsoon season, increasing its surface area from around 2,700 km² to over 16,000 km². This unique phenomenon, driven by the reversal of the Tonlé Sap River, creates a rich floodplain that supports one of the world’s most productive freshwater ecosystems.

The lake is a lifeline for millions of Cambodians, providing fish—a key protein source—for over 60% of the population. It also supports rice farming and sustains floating villages where communities live in stilted or boat houses, adapting to the lake’s seasonal changes.

Biodiversity thrives here, with over 200 fish species, rare water birds, and endangered species like the Siamese crocodile. The lake was designated a UNESCO Biosphere Reserve in 1997, recognizing its ecological importance.

However, Tonlé Sap faces threats from overfishing, deforestation, climate change, and upstream dam construction. Sustainable management is crucial to preserve this natural wonder for future generations.

A symbol of resilience, Tonlé Sap remains central to Cambodia’s culture, environment, and survival.