Si Phan Don is a beautiful set of islands, set against a scenic section of the Mekong River in Southern Laos. The Mekong is impassable to river traffic here due to the Khone Falls, a series of rapids that stretch 9.7 km (6.0 miles) of the river’s length. The Mekong below the falls has a small population of the highly endangered Irrawaddy Dolphins. The three principal islands that cater to tourists are Don Det, Don Khon and Done Kong.