Châu Đoc, in the Mekong Delta

Huddled together on dry land, homes and businesses in the town of Châu Đoc are surrounded by the floods of the Mekong Delta. Annual flooding boosts the fertility of delta land by depositing nutrient-rich sediment, and flood waters cover as much as 10,000 square kilometers (3,861 square miles). Most of that land is used for rice cultivation, which makes Vietnam a major rice-growing region of the world. The Mekong River is about 4,200 km (about 2,610 mi) long and flows through China, Laos, Myanmar (Burma), Thailand, and Cambodia before reaching Vietnam.

Alain Evrard/Photo Researchers