Vang Vieng sits on the Nam Song river between Vientiane and Luang Prabang, surrounded by dramatic limestone karst mountains honeycombed with caves. Once notorious as a backpacker party town, it has reinvented itself as an outdoor adventure destination -- though the riverside bars have not entirely disappeared.
The landscape is the real draw. The karst formations are spectacular, rising sheer from the valley floor and covered in jungle. Tham Chang cave, just across the river from town, is the most accessible and offers good views. More adventurous options include Tham Nam (a water cave you float through on a tube) and the Blue Lagoon pools at the base of the cliffs.
Rock climbing, kayaking, zip-lining, and hot air balloon rides are all available. Cycling through the surrounding rice paddies and villages is one of the most pleasant ways to spend a day. The river tubing that made Vang Vieng infamous has been toned down but still runs.
The Laos-China Railway has transformed access to Vang Vieng. The train from Vientiane takes about an hour, and from Luang Prabang around 90 minutes, making day trips or quick stopovers easy. The train station is about 5 kilometres north of town.