The Dead Sea not only has freshwater springs along its shore—En Gedi, Ein Feshka, Ein Bokek—but underneath the water’s surface as well. From the Jerusalem Post:

A Ben-Gurion University research team has discovered a series of deep freshwater springs that spring from the floor of the Dead Sea and help replenish the body’s dwindling water supply, while a German group has meanwhile pinpointed new types of microorganisms growing in fissures on the saline seafloor near the springs, the university announced on Wednesday.
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Dead Sea groundwater springs have been known and visible for decades as they produce ripples on the water surface, but the current research has given scientists to the ability to study springs that are hidden from the eye, according to the statement.
Much like the Dead Sea itself, the springs have been around for thousands of years, and while it is “uncertain” whether they’ve existed quite as long as their host body of water, they have been there “for a very long time indeed,” Laronne told The Jerusalem Post.
The springs, he continued, can be found at locations within the sea as deep as 30 meters down, and the largest spring observed thus far was 15 meters in diameter – with some spring systems totaling hundreds of meters in length.

The full story is here. The Arutz-7 report is here.