They are among the region’s most striking natural wonders, formed over millions of years by ancient rivers — and still home to mysterious secrets.
Now Saudi Arabia’s caves, sinkholes and caverns are becoming hidden gems for the adventurous or merely curious to seek out and explore.
More than 230 caves — deep and shallow, and formed of limestone, gypsum and other minerals — have been discovered in the Kingdom’s deserts.
As the mysteries of Saudi Arabia gain wider recognition, these natural treasures are the subject of growing interest.
Mahmoud Ahmed Al-Shanti, a specialist in caves and dunes at the Saudi Geological Survey (SGS), told Arab News that caves are a valuable natural asset, and attract explorers, researchers and others interested in the field.
The SGS has launched an exploration project to determine the location, types and origins of the Kingdom’s caves.
In a study titled “Caves and Sinkholes in Saudi Arabia,” Al-Shanti said that caves or sinkholes vary in size from small, where a person can barely access the main entrance, to vast, with tunnels extending for hundreds of kilometers.
The Mammoth cave in the US state of Kentucky is more than 500-km long, for example.
Caves are a rare geological, tourist and environmental asset that must be preserved and protected, he said.
“Not only are they beautiful, but some caves can be used for academic studies and scientific research,” he said.
“Countries also can benefit from them economically through financial income, career opportunities in various fields of education and research.” Al-Shanti said the western and northwestern regions of the Kingdom were home to caves and basalt tunnels between layers of lava rock near the craters of volcanoes. Examples include the Habashi cave in Harrat Al-Buqum and the Umm Jarsan cave in Harrat Khyber, about 200 km northeast of Madinah.
Caves also form in sandstone exposed to a variety of environmental factors. Examples include Qarah cave in the Kingdom’s eastern region; Al-Doudah cave, east of AlUla; and Janine cave, near Hail.
Al-Shanti said there are also sinkholes and caves in limestone rock near Saudi Arabia’s northern border, and in the central and eastern regions.
A variety of plants is known to grow in the soil surrounding these natural wonders, with roots breaking up the limestone rock over millions of years, forming long, deep corridors that branch out in different directions.
In the depths of the cave, green plants give way to organisms that can survive without sunlight. Bacteria and algae utilize waste from animals that live inside, while some use minerals in the cave as a source of food and energy.
Al-Shanti said that caves often provide shelter for mammals, including wild cats and various types of rodents.
In desert caves, carnivores, such as foxes, hyenas and wolves, live and reproduce, emerging at night to hunt before returning to the safety of the cave.
With time and effort, more hidden wonders are being discovered beneath Saudi Arabia’s sandy dunes and rocky mountains, opening the door for adventure and discovery for all.