Khone-Phapeng's waterfalls are really impressive. They are spread over 10 kilometres and can reach 20 metres high. The average flow rate, even if it doesn't mean much to you, is 11,000 m³ and in the rainy season can reach 49,000 m³. In essence, this results in incredibly powerful waterfalls which make you feel really small. The noise they make doesn't help and only reinforces the impression. You can understand the meaning of the expression "a force of nature"...
I saw these waterfalls during the dry season, when the flow was at its lowest and you can see the multitude of rocks which create all the waterfalls. During the rainy season the volume of water is much larger and everything is covered by a gigantic flow of water which seems unstoppable. Not to be missed during your trip to Laos!