Malham cave, Salt cave in Mount Sodom, Israel

Malcham Cave is a salt cave in Mount Sodom, near the Dead Sea, and the longest salt cave in the world at about 10 km. It is an underground stream with five main tributaries — Sis, Southern, Central, Northern and Sandwich — that join and exit as one channel near Route 90. Most of its 24 openings are vertical, and much of the cave has two levels: a lower one where floodwater still flows and a wider upper one formed about 5,000 years ago.

Amos Frumkin, head of the Israel Cave Research Center, discovered the cave on 21–24 December 1981, during Hanukkah. Early surveys with older instruments gave a length of 5.5 km, and until 2006 it was considered the world's longest salt cave. In March 2019 a new survey with modern equipment, led by Frumkin, measured about 10 km, restoring the title.

The cave's name, Malcham, is the Hebrew acronym of the Israel Cave Research Center, which discovered it. The center's teams, led by geologist Amos Frumkin, mapped the passages and published the surveys that established the cave's record length.

Entry into the cave is forbidden, and tours inside are complex and require certified guiding. The system has 24 openings, most of them vertical, and two main levels: floodwater now flows through the lower level, while the upper level is wider. The passages connect into a single channel that reaches the surface near Route 90.

Scientific measurements from 2019 confirmed this cave as the world's longest salt cave system. This surpassed the previous record that had been held by a cave in Iran.