Tonlé Sap

Pointing to the murky waters of the Tonle Sap, Si Vorn fights back tears as she recalls her four-year-old daughter dying from diarrhea after playing in the polluted lake.

Her family of 12 is among 100,000 people living in floating houses on Cambodia's vast inland waterway, and while their village has 70 houses and a primary school, it has no sanitation system.