There is still more than one billion tons of ore left in the mine, which is extracted using machines and underground blasting, according to a 1971-79 survey.
This is the salt mine outside of Cankiri in Turkey which began being mined in 300BC and is still in use today,
These photos were taken by 32-year-old Melih Sular who was guided through the caves by Murat Danaci as part of the National Geographic photography contest.
“When I first entered the salt cave I was afraid. I thought to myself: ‘What happens if it collapses?’
The original miners were Hittites, an ancient race of people who had an empire in the Middle East and used primitive tools and their hands to extract the salt.
“The cave is cool and scentless, which is because it is a very old salt cave. The walls are all made of rock salt and the texture is varied because of the digging machines used.
“I’ve never seen anything like it before. The most striking part of the caves is the old gallery, which were dug by Hittites,” Danaci says. “It’s interesting because they dug this gallery with simple tools and their own hands, unlike today’s methods.”
While temperatures in Cankiri can reach a balmy 92 degrees, the temperatures in the salt mines never stray above a crispy 59 degrees.
The pictures were taken by Melih Sular, 32, as part of the 2013 National geographic photography competition.
The mine’s creators, the Hittites were an ancient race who built an empire in the Middle East which covered most of modern-day central Turkey, northern Syria and Iraq and flourished between 1,400 and 1,200 BC.
Famous for their skill in building and making chariots, Hittites wrote in a hieroglyphic-type language called cuneiform.
The mine produces about 500 tons of salt every day which is sold on for use in cooking and as souvenirs.
They Hittites were eventually wiped out after several costly wars, particularly a defeat to the army of Ramses II, pharaoh of the Egyptians. Competition for succession of the throne also drained their resources.
The mine today has 16 workers and contains a small canteen, a mosque, repair room, workshop and a first aid room.
All the ore extracted from the mine, which measures in at around 90 percent purity, is taken by diggers to nearby railway tracks where it is transported to a factory for processing.