The Son River, flowing through the heart of Phong Nha commune, is typically a jade-green paradise in the summer. Known for its crystal-clear waters in the dry season, the river presented a starkly different, muddy appearance on 12/7.

The Son River flowing through Phong Nha commune on the morning of 12/7.

The Son River is an integral part of the Phong Nha - Ke Bang National Park, a UNESCO World Heritage Site. Originating from Phong Nha cave, the river meanders through limestone mountains, creating a breathtaking natural landscape.

The normally pristine view of the Son River from above, with its picturesque villages, limestone karsts, and crystal-clear water, is now obscured by muddiness.

Locals report that the river typically becomes murky during the minor flood season in summer. However, clarity usually returns within three days. This year marks an unprecedented period of prolonged murkiness. "Since June, in addition to unseasonal floods, the river has been rising and turning muddy for the past week," said Tran Van Hung, a boat operator.

The boat dock for Phong Nha cave tours presents a different scene than usual on the Son River.

Beyond its scenic beauty, the Son River is steeped in local legends and historical narratives. It also plays a vital role in the lives of local communities, providing water and livelihoods.

Ha, a visitor from Hanoi, shared that her family planned their Phong Nha trip six months in advance. Research suggested April to August as the ideal time to visit, with dry weather facilitating travel and sightseeing.

"I was taken aback by the strong, muddy current. I couldn't enjoy the clear water as I'd hoped, but since we were already there, we decided to buy tickets and experience the cave," she said.

Tourist boats navigate the murky waters of the Son River towards Phong Nha cave.

Each boat, costing 550,000 VND and accommodating 12 people, offers a 2-3 hour tour. Phong Nha cave is a must-see destination in Quang Tri province.

After a 30-minute boat ride, visitors reach the mouth of Phong Nha cave. Usually, boats enter the cave, but due to the high water levels, they now dock outside, requiring visitors to walk in.

Entrance fees are 150,000 VND per adult and 80,000 VND per child for Phong Nha cave, and 80,000 VND per adult (free for children under 1.3m) for Tien Son cave.

The entrance to Phong Nha cave, usually crystal clear in the summer, is now clouded by muddy water.

A boat operator explained that the high water level prevents boats from entering the cave without hitting the ceiling. He added that he had never witnessed such unusual rain and floods, causing the water inside the cave to become so murky and high.

The Phong Nha - Ke Bang Tourism Center has temporarily suspended tours on certain days, disrupting travel plans for many visitors.

Hundreds of boats are anchored outside the cave entrance, waiting for tourists.

The Phong Nha - Ke Bang Tourism Center regularly issues announcements to inform visitors about tour suspensions and resumptions.

Visitors explore the cave on foot, unable to experience all the attractions due to the high water levels.

Phong Nha - Ke Bang is characterized by its karst topography, featuring limestone mountains, caves, and a complex underground river system. Prolonged heavy rain causes water to rush down from higher elevations, carrying mud, silt, and sediment from the surrounding mountains, forests, and agricultural land. These impurities mix with the Son River, turning its jade-green waters murky.

To fully enjoy the clear waters of the Son River and Phong Nha cave, visitors should plan their trips carefully. After periods of heavy rain, it's advisable to wait 5-7 days for the water to clear. Checking the weather forecast before traveling is also recommended.

Dac Thanh