Investigators are baffled after discovering a cluster of huge sinkholes in a forest in China.
The 19 enormous holes - said to be among the largest in the world - were found in woodland close to where the film Avatar was shot.
Measuring almost one million cubic metres in area, the sinkholes are near the Chinese city of Baise in the southeastern region of Guangxi.
Such sinkholes are usually formed over time by water erosion when some of the ground collapses.
China's Geological Survey of the Ministry of Natural Resources reported the incredible findings.
Senior engineer Zhang Yuanhai told reporters: "It is the largest sinkhole cluster south of the Tropic of Cancer which also has the largest number.
"It is unique in this region."
Footage from the site shows an eerie, otherworldly location of forests and caverns, similar to the setting of the 2009 hit film Avatar.
This should come as little surprise, as the film was actually shot in the Zhang Jia Jie National Forest Park in Guangxi's neighbouring province of Hunan.
Inside the sinkholes, experts found lush valleys, colourful caves, stunning waterfalls and huge amounts of plant life.
The sinkholes have a volume of more than one million cubic metres and are incredibly well-preserved.
Yuanhai added: "As well as the sinkholes, the caves here are also very beautiful.
"The stalactites are well-preserved and have not been damaged."
He added that there are even palm trees at the bottom of the sinkholes.
"There are also many in the provinces of Guizhou, Yunnan and Sichuan and the municipality of Chongqing and the city of Hanzhong as well," he went on.
As remarkable as the find is, it is not the first of its kind discovered in China in recent years.
In 2014, a team of scientists found 50 huge sinkholes in the central-northern Chinese province of Shaanxi.