One of the most beautiful and most unique natural phenomena in the world is the Ali-Sadr cave near the northeast of province of Hamadan in the heart of the Subashi mountains, Iran. This natural phenomenon is the only cave in the world in which yachting is possible in its underground waters. The small boats shown here are a convenient way to let the men in front peddle you along some fresh water caverns where the water reaches at least 14 metres in places. Over 11 km of corridors of the cave have so far been discovered.
