River that forms much of the Laos/Thailand border Crossword Clue

 The river that forms much of the Laos/Thailand border is the Mekong River. It is the longest river in Southeast Asia, and the 12th longest river in the world. It flows through China, Myanmar, Laos, Thailand, Cambodia, and Vietnam. The Mekong River is a vital source of water and food for millions of people in the region. It is also an important transportation route and a source of hydroelectric power.

The Mekong River forms the border between Laos and Thailand for about 850 kilometers. The border is often marked by the river itself, but there are also a number of islands and other features that help to define the border. The Mekong River is a major trade route between Laos and Thailand, and it is also a popular tourist destination.

The Mekong River is facing a number of challenges, including climate change, pollution, and dam construction. These challenges are threatening the river's ecosystem and the livelihoods of the people who depend on it. However, there are also a number of efforts underway to protect the Mekong River and ensure its sustainability for future generations.