On the Mekong, the journey doesn't take you somewhere — it reveals you to yourself. The Mekong River stretches more than 4,350 kilometers from the Tibetan Plateau to the South China Sea, flowing through the heart of Southeast Asia before spreading into the Mekong Delta in southern Vietnam. A luxury Mekong River cruise between Vietnam and Cambodia typically spans seven to fourteen nights, following the route from the delta upstream to Siem Reap in Cambodia.