Tham Poukham - Blue Lagoon, (7 km west from town, accessible by mountain bike or motorbike). 8AM-6PM. Well signposted, with a number of other sites en route. The toll bridge in town on the way costs 10,000 kip. 10,000 kip more to enter the lagoon/cave site. The lagoon is a small pond, no more than 10m wide, and surrounded by a parking lot, vendors, and tables. On most days, it is plenty crowded, with tourists practically landing on top of each other from the rope swing. Super crowded with Laos families at the weekend, it's a nice spot for a family picnic but hardly an exciting day trip in its own right. There's a water slide - you guessed it, 10,000 kip. The cave above is decent. A modest 100 m climb up rocks and stairs. Once inside, there is a short walk to the Sleeping Golden Buddha and glimmering stalactites about 300 m further inside. Take a head torch or rent one for 10,000 kip, essential if you go deeper into the cave than the Buddha (check the battery in advance). Guides for the cave advertised at 50,000 kip but this is probably negotiable. Guides probably not necessary since the path inside is well worn and marked in spots. Don't fall down the holes towards the back. Lagoons 2, 3, and 4 are less crowded, but beware the muddy roads!