Koteshwar Mahadev Cave is in Bela Gaon on the banks of Alaknanda – The holy river. Three times in an year Alaknanda visit the holy cave. It is said when Kurukshetra war was over, Kaurav brothers were killed by Pandavs an Akashvani (heavenly voice) suggested Pandavs to pray Lord Shiva for Mukti (salvation).
Lord Shiva was present within the cave meditating and Pandavs in-search of Lord Shiva. The moment it is known to Lord he shifted from the cave towards Kedarnath. At that time the demons (BrahmaRakshas) residing close to the cave requested Lord not to leave but Lord Shiva was not willing to stay to grant Mukti to Pandavas as he thought maybe in future each person will do the same (killing act) and will ask for Mukti (salvation). Finally before moving Lord Shiva granted demons (BrahmaRakshas) a boon and i.e., whoever visit the cave wishes will be fulfilled. Devotees now-a-days visit cave mostly to pray to have children.