The Donglisa River is the largest freshwater lake in Cambodia and Southeast Asia. It is also the first river in the world to reverse its flow due to different seasons. Phnom Penh, the capital of Cambodia, is located on the Tonlisa River. Every year during the rainy season from June to September, the Mekong River flows into the Donglisa River, causing the Donglisa River to surge, with a large amount of water and a turbid yellow water quality. During the dry season from December to May of next year, the water of the Donglisa River flows into the Mekong River to supplement the water of the river. Going to Phnom Penh, you can enjoy the scenery along the Donglisa River by the second-floor cruise boat. The Grand Palace of Phnom Penh is located in the area along the river, and you can also enjoy the scenery of the Donglisa River in the sunset in the evening.