Muang Ngoi Neua, Laos 2002. The only way to get up there is by boat, it feels like an island but it isn't. We have been back a few times over the years, making our way up the Nam Ou (river). It's still a nice place to stay and head out into rural Laos if you don't mind a stiff walk. It's mainly populated by tourist nowadays (not like Vang Vieng Though) and the best time to visit is on market day. Make your way to one of the parties when the market comes to an end, be prepared for the hangover afterwards as they love sharing their Lao Lao.
Most people go up the Nam Ou from Nong Khiaw, but you can go downstream from Muang Khua.
