The largest river in this province, the Gamasiab, passes through the provinces of Kermanshah, Lorestan, 11am, and Khuzestan where it is known as Karkheh. The mineral water spring of Tangez provides gaseous water that contains bicarbonate of chlorine and is said to be effective in curing the diseases of the digestive system, liver, stomach and the abdomens. The cave of AliSadr, 80 km north of the city of Hamedan, and close to the city of Kabudarahang is the largest and most renowned cave in Iran and one of the most impressive in the world. Its length is estimated to be something between 11 and 17 km although it has not yet been entirely explored. It is a collection of large “halls”. Clear and pure water covers the floor. Calcium carbonate sediments have given rise to the formation of staggeringly beautiful stalagmites hanging from the ceiling, the like of which is difficult to find anywhere in the world. The levels of light, temperature and relative humidity at any point in the cave, remain constant throughout the year. Tourists can visit the different parts of the cave by boat. This cave is the most visited (one million people a year) natural phenomenon of Iran, Sard-kooh, and Ghalejoogh caves, and caves number 1, 2 & 3 are among the other many caves of this province. This province has many undulations: mountains, plains and valleys, which provide the right conditions for the growth of many plants and vegetation. The green nature of this province attracts many tourists. For instance, there is a forest close to the city of Nahavand which is a great favorite with those tourists who are in search of natural beauty. The province also has many preserved areas where a large number of protected species can be found, e.g. the wild goat, ram, fox, brown bear, weasel, as well as many birds such as the partridge. The Alvand mountain range is the province’s largest. Alvand peak, close to Hamedan city, has a ski slope 4 km long, with an inclination of 25%. Chelnabaleghan mountain peak, 4,200 m high, is the province’s highest. Kalaghlan 3,500 m, Chahar-ghaleh, and peak Yekehchaal, 3,580 m are other important mountain tops of the province.