Lord Kṛṣṇa saw how the Kāliya serpent had polluted the Yamunā River with his terribly powerful poison. Since Kṛṣṇa had descended from the spiritual world specifically to subdue envious demons, the Lord immediately climbed to the top of a very high kadamba tree and prepared Himself for battle. He tightened His belt, slapped His arms and then jumped into the poisonous water.