The 10-kilometer Malham Cave in Israel’s Dead Sea region is the world’s longest salt cave.

Malham was initially discovered by the Cave Research Center in the 1980s inside 11-kilometer-long Mount Sodom. At 170 meters below sea level at the southwestern tip of the Dead Sea, this mountain is composed entirely of salt underneath a thin layer of cap rock.

Every winter, rainstorms dissolve more salt and create new passages. So when the international expeditions returned to Malham in 2018 and 2019, they discovered the cave had a double-digit length, breaking the record held for the past 13 years by Iran’s Cave of the Three Nudes on Qeshm Island, measuring 6,580 meters long.