Kumaradhara Theertham in tirumala

Kumaradhara Theertham is believed to be the place where Lord Vishnu took penance after killing the demon named Tarakasura. It is also believed that a devotee of Lord Vishnu lost his way in the hills and started meditating. Lord Vishnu appeared before him and asked to take a bath in this pond. This holy dip transformed the man into a sixteen year old boy and the pond came to be known as Kumara Theertham.