Einot Tzukim is a nature reserve on the highway towards Ein Gedi. Three areas: main one is some man-made swimming holes. Second area is accessible only as part of a guided tour. There is also an entirely closed off section of the reserve.
The second area is the one that is interesting. There are pools created by rainwater that runs off from Jerusalem and also an ecosystem of reeds, palm trees and other flora and fauna. Some of the animals are said to be unique to the area. We saw a particular type of Amnon fish in a shallow pool. The guide also described unique cicadas, ants, and a particular kind of bird. We did not see these however.
The reserve used to include the edge of the Dead Sea, but the sea has vastly receded in recent years. The pools themselves are moving location to the changes to the Dead Sea topography.
13 minutes ago