Discovered in 1963 by Iranian mountaineers Ali sadr or Ali Sard (Ali Cold) is the largest water cave in the world. It is located in the southern part of Ali sadr village in the county of Ali sadr Kabudarahang, 100 kilometers north of Hamedan. It is high recommended tourist attraction and tours of the cave are available by paddle boats. The entrance of the cave is from a side of Sari Ghiyeh hill which includes two other caves Sarab and Soubash. The first one is the source of the water in Ali Sadr cave.
According to a German/British expedition report in 2001, the cave is 11 km long. Walls over 40 meters and several long and deep lakes are found in the cave. Ancient artworks, jugs, pitchers and animal pictures dating back to 12000 years ago have been discovered through excavations and archeological studies.
A verified old description at the entrance of the cave suggests that the cave was know during the reign of Darius-the Achaemenid King.