The Khone Falls and Pha Pheng Falls is a waterfall located in Champasak Province on the Mekong River in southern Laos, near the border with Cambodia. The Khone Falls are the largest in Indochina and they are the main reason that the Mekong is not fully navigable into China. The falls are characterised by thousands of islands and countless waterways, giving the area its name Si Phan Don or 'The 4,000 islands'.
The highest falls reach to 21 metres (69 ft); the succession of rapids stretch 9.7 km (6.0 mi) of the river's length. The average discharge of the cataract is nearly 11,000 m3/s (390,000 cu ft/s), with the highest flow on record at over 49,000 m3/s (1,700,000 cu ft/s).
The Khone Phapheng falls are the main reason why the over 4,000 kilometer long Mekong river is not navigable by ship from China downstream into the South China sea. In the 19th century, when Laos was part of French Indochina, the French tried to establish a shipping route in an attempt to connect the countries of French Indochina to the sea. After several attempts to navigate the falls by ship had failed, they decided to go around the falls by building a railway and a railway bridge between Don Det and Don Khon islands.
he Khone falls are located South of Don Khon island, the area which is the home of a small group of rare Irrawaddy dolphins. At the highest point the waterfall is 21 meters high. Just above the Khone falls is a viewpoint with a pavilion providing great views over the waterfalls and numerous islands.