Big Waterfall Khone Phapheng
Watch the fishermen effortlessly jump from rock to rock through the rapids as they tend to their traps. Listen to the water roaring over Khone Phapheng falls, the largest falls in Southeast Asia and the reason boats can’t transverse the Mekong to China. The falls are home to the huge, and endangered, plabuck catfish, which can grow up to 3m (10 feet.) The fee to enter the falls for foreigners is 55,000 kip ($6.60 USD) and includes a shuttle around the property.
Irrawaddy Dolphins
Old French Railroad Locomotive
An outdoor display on Don Khon shows a rusted French engine from the late 1800s, when the French built a 7km railroad line to bypass Khone Phapheng falls and create a trade route from Cambodia up the Mekong to Laos and eventually China. The French loaded the boats onto rail cars below the falls then put them back in the water above the falls. The operation was abandoned in 1940 when a road was built around the falls. Today, you can check out the display and stand on the bridge between Don Det an Don Khon, which was formerly for trains but is now open to foot traffic and two-wheeled vehicles.
Watch the sunset
Anywhere western-facing is a great place to stop what you’re doing at 6 pm and watch the sun sink over the Mekong River, making the water sparkle. One favourite place to watch the sunset is from the historic French railroad bridge that connects Don Det and Don Khon. Lao people and visitors alike flock to the bridge around 5 pm to chat and watch the brilliant colours light up the sky. Bring a headlamp or flashlight to help you navigate back to your guest house after the sun goes down. With no streetlights, the bumpy dirt roads and bamboo bridges can be especially challenging to navigate at night.
According to theculturetrip.com