Blue Lagoon 1 sits at the base of the karst cliff below Tham Phu Kham cave, and most visitors combine the two in a single trip. The lagoon itself is a natural pool fed by underground springs, and the water remains a consistent turquoise colour year-round. Trees shade the edges and there are platforms for jumping.
Weekends and Chinese New Year holidays bring large crowds, mainly domestic Lao and Chinese tourists. If you can visit on a weekday morning you'll have a very different, quieter experience. The site is fenced and charges a small entry fee. Food vendors sell drinks and snacks near the entrance.