A small boat quay on a lake at the bottom of Turda salt mine in Turda, Romania (450km northwest of Bucharest) on December 9, 2010. One of the most important salt mines in Transylvania, Salina Turda has been known since ancient times, but was put into operation for underground mining work during the Roman period.
Since 1992, Salina Turda is a halotherapy center and a popular tourist attraction. which looks pretty amazing.
More underground stuff here.
...
