Si Phan Don, Laos
Si Phan Don, aka 4000 islands, is the southern-most point of Laos where the Mekong river breaks into pieces leaving a bunch of islands in between. Don Det is the one packpackers prefer. I spent 4 nights there and loved every minute of it!
Those 4 days consisted of a lot of swimming, floating around in a tube and swimming in between islands, laying in a hammock, reading, eating very very well (in this most amazing Indian restaurant), having campfires on the beach...