Slănic Prahova Salt Mine. This mine is the biggest salt mine from Eastern Europe, measuring over 50,000 m2. It is located at a depth of over 200m. It is unique in Romanian and in Europe, through its dimensions; the salt mine is made out of 14 rooms, in the shape of a trapezium and has an opening at the base of 32 m, a 14 m tray, and a height of 45 m. The excavated space is 2.9 million m3.
The access in the mine is done with two elevators which carry the visitors between the underground levels and the surface, through a difference in elevation of about 200 m. There are tunnels which carry the air inside the mines and the inside temperature is about 12°C throughout the year. The air in the mine is rich with sodium ions, which have prophylactic and beneficial effects in all respiratory deficiencies and diseases. Other natural places which have curative properties are The Old Salt Mine (Unirea), which is now a sanatorium for the treatment of rheumatic diseases in a salty air microclimate, at about 200 m deep. You can also find playgrounds for the kids, a sports field, a room with pool tables and a buffet. You also have the opportunity of taking warm mineral water baths in tubs, cold baths in the lake, warm mud therapies. Slănic also has mineral water springs and lakes Baia Baciului, Baia Roșie, Baia Porcilor, Lacul Verde, with a high salt content.