The four thousand islands have three main destinations for travelers. Si Phan Don is characterized by numerous islands, half of which are submerged when the Mekong River is in flood. The Don Khong is the biggest, but apart from the usual chill look there are not too many activities to participate in there. Most people head to Don Det or Don Khon, where accommodation is cheaper, you can walk to one of the big Mekong-Falls by yourself, and biking and walking and swimming in the river is just the same as in Don Khong. Freshwater Irrawaddy dolphins can be spotted by boat off Don Khon Island. The Khone Phapheng Falls are also a great place to go and view the raging rapids and enjoy the beauty surrounding this location.