An incredible cave network has been discovered 700ft below a national park.
Stunning pictures show a "wondrous" blue pool - never before been seen by human eyes - which was found in the depths of Carlsbad Caverns National Park in New Mexico.
The alien-like pool contains milky aquamarine liquid, surrounded by white frosted rock, the Kansas City Star reports.
It is believed that the cave has evolved over thousands of years and has been completely untouched by humans.
"This pool has been isolated for hundreds of thousands of years and had never seen light before that day," explains Rodney Horrocks, chief of natural and cultural resources at Carlsbad Caverns National Park.
The eerie discovery was made 700ft below the entrance of Lechuguilla Cave, one of the 10 longest caves in the world.
Although it was discovered in 1993, explorers only entered its "virgin" passages for the first time in October.
Posting news of the discovery on Facebook, geoscientist Max Wisshak said: "Exploration in caves sometimes yields wondrous sights."
"This cave pool, found in Lechuguilla Cave, appears to be completely pristine.
"The edges beneath this pool appear to be ‘pool fingers’, which could be bacterial colonies that have evolved entirely without human presence."
The expedition, led by Wisshak, involved mapping out 1.3 miles of passages and multiple "rope drops".
It is not known when the cave network was formed.
Although no visible signs of life were found, the expedition did come across numerous bat skeletons, believed to be thousands of years old.
The pool is approximately one foot wide, two feet long and several inches deep.
Although it appears to be cloudy in pictures, the pool is actually crystal clear and is most likely ancient filtered rainwater which seeped through the cave's limestone.
"Such untouched pools are scientifically important because water samples are relatively free of contaminants and the microbial organisms that may live in those pools are only those that belong there," Wisshak continued.
"Contamination can occur from the surface above the cave, but in case of Lechuguilla Cave, that’s not a big issue, since it is situated in a well-protected wilderness area. It can also occur via aerosols in the air.
"However, a newly discovered pool in Lechuguilla Cave is about as pristine as it gets."
The cave network contained several similar pools, the largest of which has now been named the "Lake of Liquid Sky".
https://www.mirror.co.uk/news/world-news/incredible-pool-untouched-humans-discovered-22150863
