Ali Sadr Cave

Ali Sadr Cave lies beneath the hills of Kabudarahang County, north of Hamadan, by the village whose name it bears. It is one of the largest water caves in the world: much of its length is flooded, and visitors travel through it by boat, gliding along channels of clear, cold water between walls and ceilings hung with limestone formations.

Local people had long known of the cave, but its exploration in modern times began in 1963, when members of a Hamadan mountaineering club entered it and found their way deep into its passages. A German and British expedition surveyed it in 2001 and measured more than 11 kilometres of passages; only a part of this is open to visitors. The water stays at a cool, steady temperature all year, and the air inside is still and damp.

The visit begins with a boat journey of several hundred metres through flooded galleries, lit by lamps that pick out stalactites, curtains of stone and tall chambers. In places the boats stop and visitors walk along dry passages before boarding again. Some formations have been given names by guides, and the echo of voices over the water adds to the strangeness of the place.

The cave has become one of the most visited natural attractions in western Iran, with a tourist complex at the entrance, and in holiday seasons the queues can be long. Bring a warm layer, even in summer. Above ground, the dry, rolling hills of Kabudarahang give no hint of the water beneath them, which makes the descent into the cave all the more surprising.