There are many beautiful caves in Iran which some are mentioned here: Namakdan cave which is the longest known salt cave in the world, Ali Sadr cave in Hamadan and Saholan cave in Mahabad that water flows in them and allows boat-riding inside the cave, Paraw cave in Kermanshah which is one of the deepest cave in the world, Chal-e Nakhjir cave that is known for its special white dolomite alluviums covering the floor of major corridors of the cave and Katale Khor cave located near the city of Zanjan. Another category of Caves in Iran are historical caves such as: Shekarchyan cave in Kermanshah, Karaftu cave in Kurdistan and Humyan and Kalmakareh in Lorestan.