27,000 years: the age of the cave paintings of Cosquer
Cosquer Cave, located in France near Marseille, was discovered in 1985 by Henri Cosquer. The rocks inside the cave are all covered by paintings made 27,000 years ago.
Currently, the entrance to the cave is 37 meters below sea level, so visitors are not allowed to go in: the cave can only be accessed by divers through a 175-meter long tunnel.
At the time the paintings were done, and the locals used the cave for ceremonies, the sea level was well below the current level and many kilometers away from the present coast.
It was the time of the last great ice age when large volumes of water were frozen at the poles and billions of gallons of water were locked away in vast continental ice sheets.