Although the therapeutic properties of the Wieliczka salt has been known already in the 16th century, only in the 19th century it was discovered that staying in the mine has a beneficial effect on health. Research has shown that asthma treatment provided in the region is very effective. Wieliczka spa organizes therapeutic stays 135 metres underground in the chamber "Lake Wessel". This unique treatment is a way to recover not only health but also well-being in a strange underground world where one has unforgettable experience.