Si Phan Don (Lao: ສີພັນດອນ; meaning The 4000 islands) is a riverine archipelago located in the Mekong River, Champasak Province in southern Laos.
Si Phan Don is characterised by numerous islands, half of which are submerged when the Mekong River is in flood. The principle islands of Si Phan Don are Don Khong (the largest), and Don Det and Don Khon.
Key features of the Si Phan Don archipelago include:
The remains of the first railway in Laos, the Don Det – Don Khon narrow gauge railway, built by the French to bypass the Khone Phapheng Falls and enable vessels, freight and passengers to travel along the Mekong River.
Freshwater Irrawaddy dolphins (Pakha) that can be viewed by boat off Don Khon island. They are considered highly endangered.
The Khone Phapheng Falls, a succession of impassable raging rapids that gave rise to the construction of the railway.
Timber was historically logged on the islands but it is now regulated; illegal logging incurs stiff penalties.
While the local economies are predominantly based on agriculture, the Si Phan Don archipelago has seen an increasing number of visitors wishing for a 'picture-perfect' experience of Laos. However, tourists numbers are concentrated on Don Khong, and Don Det and Don Khon, and many of the smaller islands remain rarely visited.