originally called Ali Saadr or Ali Saard (meaning cold) is the world's largest water cave which attracts thousands of visitors every year. It is located in Ali Sadr Kabudarahang County about 100 kilometers north of Hamadan, western Iran (more accurately at 48°18'E 35°18'N). Because of the cave's proximity to large cities such as Hamadan, it is a highly recommended destination for tourists from all corners of the world. Tours of the cave are available by pedalos.
Alisadr is the world's largest water cave, where you sit in a boat and watch the view. This cave is located at 48°18'E 35°18'N, in the southern part of Ali Sadr village. The cave is entered at the side of a hill called Sari Ghiyeh which also includes two other caves called Sarab and Soubashi, each 7 and 11 kilometers from Ali Sadr Cave. Apparently, the water in Ali Sadr cave stems from a spring in Sarab.
In the summer of 2001, a German/British expedition surveyed the cave, finding to be 11 kilometers long. The main chamber of the cave is 100 meters by 50 meters and 40 meters high.
The cave walls can extend up to 40 meters high, and it contains several large, deep lakes. The cave has a river flowing through it and most travel through the cave system is done by boat. More than 11 kilometers of the cave's water canals have been discovered so far. Some routes are 10 to 11 kilometers long and all lead to "The Island", a centrally located large atrium.
The temperature of the cave is always the same 16 is the air and 12 the water.PH is almost neutral and depth of water is measured between 0.5 to 14 meters. The water hardness is high and of lime, therefore it is not suitable for drinking. Alisadr cave is a live cave and there is no poisonous gas in it and there is no shortness of breath because air flows in naturally. Also there is no living organism in the cave due to lack of sunlight. The interesting point is that the cave is of consolidated types so that in the last five million years no rocks have fallen down, since the stalactites and stalagmites are seen of the same age. By the way until now, 11440 meters of the passages of the cave has been identified in different stages and about 2.2 kilometers is being visited by enthusiasts.