16 / Subduing Kāliya
When He understood that the water of the Yamunā was being polluted by the black serpent Kāliya, Lord Krṣṇa took action against him and made him leave the Yamunā and go elsewhere, and thus the water became purified.
When this story was being narrated by Śukadeva Gosvāmī, Mahārāja Parīkṣit became eager to hear more about Krṣṇa's childhood pastimes. He inquired from Śukadeva Gosvāmī how Krṣṇa chastised Kāliya, who was living in the water for many years. Actually, Mahārāja Parīkṣit was becoming more and more enthusiastic to hear the transcendental pastimes of Krṣṇa, and his inquiry was made with great interest.
Śukadeva Gosvāmī narrated the story as follows. Within the River Yamunā there was a great lake, and in that lake the black serpent Kāliya used to live. Because of his poison, the whole area was so contaminated that it emanated a poisonous vapor twenty-four hours a day. If a bird happened to even pass over the spot, he would immediately fall down in the water and die.
Due to the poisonous effect of the Yamunā's vapors, the trees and grass near the bank of the Yamunā had all dried up. Lord Krṣṇa saw the effect of the great serpent's poison: the whole river that ran before Vṛndāvana was now deadly.
Krṣṇa, who advented Himself just to kill all undesirable elements in the world, immediately climbed up in a big  kadamba  tree on the bank of the Yamunā. The  kadamba  is a round yellow flower, generally seen only in the Vṛndāvana area. After climbing to the top of the tree, He tightened His belt cloth, and, flapping His arms just like a wrestler, jumped in the midst of the poisonous lake. The  kadamba  tree from which Krṣṇa had jumped was the only tree there which was not dead. Some commentators say that due to touching the lotus feet of Krṣṇa, the tree became immediately
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