The Kong Lor cave in Laos' Phou Hi Pun National Park is the longest cave in the country, with 7 km of river flowing through it. The cave is nestled in a beautiful area surrounded by sticky rice fields in the wet season and tobacco in the dry season. The trip through the cave is done on a motorboat you can hire at the entrance to the national park. The passage is dark and wet, but certain parts of the cave are walkable and lit to show the formations. Exiting the cave on the other side is another beautiful experience as you pass by water buffalo and small children playing in the river. The whole trip is worth it due to its isolation and natural beauty.
You can get here by motorbike or a bus from Thakhek, which is the closest city. There are guest houses located in the farm area leading to the cave.