Israel, located in the Middle East, has a semi-arid climate. It is still influenced by the Mediterranean Sea, which allows sufficient rains in the coastal areas during winter. But a mountain range, running north to south along the coast divides the country. Jerusalem sits on the top of this ridge, to the east is the most interesting geologic structure of the country: the Dead Sea graben.
A graben is an elongated, relatively depressed crustal unit bounded by faults on both sides. It is caused by a divergent movement of the plate. The plate widens and faults form, which results in a subsidence of the crust between two of the faults. Once it is deep enough seawater will flow in and the graben will become a new ocean, slowly but continually widening. This is how the Atlantic Ocean started many million years ago. This geologic structure was first described in German, that's why the German term Graben (literally ditch) is used internationally as the geologic term.
The numerous limestone and sandstone layers of the Israeli mountains allow the water to pour from the west flank to the east. Several springs along the Dead Sea form each an oasis. This allows several settlements in the Judean Desert.
The country has huge limestone karst areas. The caves are around comfortable 20 °C warm. But unfortunately there is only one show cave.
Very common all around the country are small natural caves and abris (shelters). They were used during 3,000 or 4,000 years of history as shelter, housing, storage rooms, barns and churches.
All this applies to the northern part of Israel. The southern part of the country is the Negev desert, which is mostly flat. Beautiful landscape, interesting geology but no underground sights we know of.