The Mekong River is one of the longest rivers in the world. It is over 3000 miles long, and starts in Tibet, goes down Yunan Province, crosses Myanmar, Thailand, Laos, Cambodia, and then goes into the ocean in Vietnam. The landscapes is lovely, I was close to Mekong on the Myanmar side, a little in Thailand, but mostly in Laos, in the Luang Prabang region. You feel that life is punctuated by the lake, trade, transportation of people, and most of the business is done in the river, because the roads are not in good condition. For visitors, I recommend that you find out the travel times , which arent always clear, but they may give you an idea, because if you go up or down the river, the same journey can take 1 to 3 days.