Gandaki River is of great religious importance in Hinduism. There are numerous stories associated with Gandaki River and one story is associated with the Mohini Avatar of Bhagwan Vishnu. The origin of the river is associated with the story of the churning of the ocean of milk by the devas and the asuras. At that time, when Vishnu took the form of Mohini, she was attracted by Shiva. The sweat produced at the time of their embrace overflowed as Gandaki River through Earth.
Gandaki River is also worshipped as Narayani, Salagrami, etc. About the holiness of the river, there is another story. Once some worms were collecting soil from its banks, they fell into the water and attained moksha immediately. From that day onwards, people started worshipping her, realizing her greatness.
In the Mahabharata, it is highly extolled and said that the water of this river is a mixture of all holy river. Therefore, a bath in it is equal to conducting an Ashvamedha Yajna, and one will attain Surya Loka afterwards.