World's longest salt cave found in Dead Sea’s Mt. Sedom, 'biblical' Israel

The cave is 10 kilometers long.

Malham Cave
Israeli researchers discovered the world’s longest salt cave: Malham Cave in the Dead Sea’s Mount Sodom area, measuring 10 kilometers long.
An international expedition led by the Hebrew University of Jerusalem’s Cave Research Center (CRC), Israel Cave Explorers Club and Bulgaria’s Sofia Speleo Club – along with 80 cavers from nine countries – recently completed mapping the cave.
 “Thirty years ago, when we surveyed Malham, we used tape measures and compasses,” explained Prof. Amos Frumkin, director of the CRC at Hebrew University’s Institute of Earth Sciences. “Now, we have laser technology that beams measurements right to our iPhones.”
This technology helped the team to determine the cave’s record-breaking, double-digit length.
Malham was initially discovered by the CRC back in the 1980’s. Further CRC expeditions surveyed Mount Sodom and found more than 100 different salt caves inside, the longest of which measured 5,685 meters. Subsequent carbon-14 tests dated the cave at 7,000 years old, and that successive rainstorms created new passages to explore.
This new record was only discovered when international expeditions returned to Malham in 2018, supported by the Bulgarian Federation of Speleology, the Ministry of Youth and Sports in Bulgaria, the European Federation of Speleology and its sponsors – Aventure Verticale, Korda’s, Scurion and Bulgaria Air.
Malham is the world’s first salt cave to reach a double-digit length; previously the longest cave was only 6,580 meters and the title of world's longest cave was held by Iran's Cave of the Three Nudes on Qeshm Island. Currently, the survey team is processing final data from the surveys to create an electronic map of the cave and to publish its findings. 
Geologically speaking, salt caves are living things, according to an explanatory release by Hebrew University. They form mostly in desert regions with salt outcrops. What helps them form is water – even arid climates see the occasional rainstorm. When it does rain, water rushes down cracks in the surface, dissolving salt and creating semi-horizontal channels along the way. After the rainwater drains out, these dried out “river beds” remain and salt caves are formed.
“The Malham Salt Cave is a river cave,” said Frumkin. “Water from a surface stream flowed underground and dissolved the salt, creating caves – a process that is still going on when there is heavy rain over Mount Sodom about once a year.”
Mount Sodom is named after a location mentioned in the Book of Genesis, describing how Lot’s wife became a pillar of salt after she looked back at Sodom.
“Mapping Malham Cave took hard work,” said Efraim Cohen, a member of Hebrew University’s research team. “We cavers worked 10-hour days underground, crawling through icy salt channels, narrowly avoiding salt stalactites and jaw-dropping salt crystals. Down there, it felt like another planet.”