46 Bhagavatha -- Kaliyamardhana

In the bed of Yamuna, there was a pool inhabited by the serpent Kaliya. The water was being constantly boiled by the fire of its poison. Birds flying over it fell down dead. Touched by the wind which blew over the ripples of that poisoned water, living beings, mobile and immobile met their death.
Once Krishna went to the banks of Kalindi (Yamuna) along with his friends. Balarama did not accompany him. Oppressed with the summer heat and thirst, the cows and cowherds drank the polluted water contaminated with Kaliya's poison. They all fell dead. Krishna, by his mere gaze, restored them all to life. They all stood amazed.
Krishna tightened his clothes around his waist and climbed up a lofty kadamba tree. He slapped his arms in a
challenging mood and jumped into the pool from that height. The volume of water swelled by the vehemence of the plunge. Hearing the mighty splash, and angered that his abode has been violated, Kaliya approached the Lord. Biting Krishna in various places, the serpent enclosed him in his coils. Krishna was sporting fearlessly with a smile on his face. But from the banks of the Kalindi, the cowherds and calves saw that Krishna was caught in the coils of the snake and he did not move. Out of fear and helplessness, some cowherds fell down senseless. Getting to know of this, Nanda and Yashoda also were overwhelmed with sorrow.  Distressed beyond words, they all headed towards the banks of the Yamuna. Only Balarama heartily laughed and said nothing.
They reach the banks and saw Krishna in Kaliya's coils, lying motionless. Their grief multiplied. Some of them held Yashoda in check, who ventured into the stream. Nanda and the other cowherds were also uncontrollable out of grief. Balarama stops them.
For some time, Krishna continued to stay there in the bondage of the serpent. Then he expanded himself and grew out of the clutches of Kaliya. Kaliya, feeling oppressed with the expansion of Krishna's body, held up his hood and stood hissing and breathing out poison. He stared at Krishna with burning eyes emitting flames through his mouth. In a sportive mood, Krishna wheeled around Kaliya quickly and caught hold of the hood and bent it. In a trice he was atop its broad hood, dancing over it. His lotus feet turned crimson due to the multitudes of jewels which adorned Kaliya's hood. Here he was the Lord, who wielded his severe punishing rod. With graceful movements, Krishna jumped and crushed whichever hood of Kaliya that did not bend.  Ejecting deadly poison and blood through its mouth and nostrils, Kaliya swooned. Whichever hood Kaliya tried to lift up was immediately beaten down with Krishna's dancing steps. Kaliya now thought of the most ancient person, Lord Narayana, and seeks him as his protector.
The wives of Kaliya, along with their children surrender and plead with Krishna to spare Kaliya's life.
"Hail to you O Lord! Be pleased and forgive the offense of this stupid creature who does not know you. You inflict punishment only because you expect good results. Even your anger is meant only to bless us. This is indeed a boon conferred on us. Tell us what we should do now, we will obey your command with reverence." Krishna spares the life of Kaliya.
The serpent gradually recovers its senses and prays to Krishna: "We are wicked since our birth, as we are
born of tamoguna. We also belong to this universe, a diversified product of the three gunas, which has been evolved by you. How then, can we get rid of your maya, by our own efforts? Show us your grace or mete out punishment as you think fit."
Krishna replies: " You ought not to stay here, O serpent! Proceed to the ocean with your kinsfolk, wives and
progeny. Let the river be used by the bovine race and human beings. Garuda, fearing whom you took shelter in this pool (leaving the island of Ramanaka) shall not devour you, as you have been marked with my footprints." Kaliya, after paying his respects to Krishna, withdraws to the island of Ramanaka with his kinsfolk. Yamuna was pure again.