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Third wave is a rock under the Mekong River. Amphoe PHO Sai in Ubon Ratchathani province. Caused by the erosion of labour became more than 3000 basin and basin are visible in the dry season the water dry knitted. Rapids they showed similar Middle Mekong River mountain water, until the locals called the Grand Canyon which is this phenomenon will occur from October-may, after which there will be a coming wave of flood water submerging them disappear under the river.

Third wave of rock beneath the river. In Pho Sai Province Caused by water erosion. A pool of more than 3,000 wells and is visible during the dry season, the water dry up. Such rocks would emerge from the water like a mountain in the Mekong River. The locals called Grand Canyon river This phenomenon will occur about a month from October to May, after which it will flood a flood wave that sinks to the river.