Vipasa is the ancient name of Beas River and it is mentioned in the Hindu scriptures. There is an interesting story as to how Vipasa River got its name.
Legend has it that a man-eating Rakshasa entered the body of King Saudasa. He then roamed around forest eating human beings. One day he devoured all the 100 sons of Sage Vasishta.
Unable to bear the loss of his sons, the sage attempted to kill himself. But all his attempts failed.
He then bound his arms and legs with strong ropes and plunged into Beas River, which was in full flow breaching its banks due to rain.
It is said that the river loosened the knots of the Sage and took him safely to one of its banks.
As it unbound and saved the Sage it came to be known as Vipasa.
The term Vipasa means unbound.