The Mekong is enormous. In the rainy season, it can be several kilometres wide. It carries so much water that whole fishing villages build their houses on stilts at the riverside to stay above the seasonal floods. When the water rises, it drops rich soil on the land around it - perfect for growing vegetables.
Fishermen on the Mekong use all kinds of tools: long nets strung between poles, round 'throw nets' that billow open in the air and sink to the bottom, and bamboo fish traps placed under the water overnight. Fishing from the Mekong feeds millions of families.
The river is also a road. Slow wooden boats carry people, vegetables, fuel and goods between villages. Before roads were built through the mountains, the Mekong was almost the only way to travel in northern Laos. People still use it today.
Every year in October or November, at the end of the rainy season, Laos holds a boat racing festival on the Mekong called Boun Souang Heua. Long wooden racing boats, painted in bright colours and carrying 50 or more rowers, race each other on the river. It is one of the biggest celebrations of the year.