Cool Spring
If you are doing the Thakhek Loop in an anto-clockwise direction, then just a few km before you get to Tha Bak, you will see a dirt road and sign post on the right leading towards ‘Cool Spring’ (https://goo.gl/maps/Jvys9e9XiVUVeaUSA).

The dirt road is in excellent condition and the 10 minute drive across open paddy fields in front of spectacular karst limestone mountains. The road leads to a secluded oasis of blue water emerging from a spring at the base of a limestone cliff. There are a few small restaurants and changing rooms here, making it an excellent place to stop and have a refreshing dip.