Third wave of rock or beneath the Mekong giant's kettle. Pho Sai district in Ubon Ratchathani Province Caused by water erosion. A pool of more than 3000 wells and are visible during the dry season, the water dried up. Such rocks would emerge from the water like a mountain in the Mekong River. The locals call Grand Canyon river This phenomenon occurs about a month from October to May, after which it will flood a flood wave that sinks to the riv