Gajendra moksha means "Liberation of Gajendra" and is a popular tale from the Bhagavata Purana. While bathing in a lotus-filled lake, Gajendra, the king of elephants, disturbed a makara who grabbed his leg and began to pull him under water. Trapped within the makara's strong jaws, Gajendra tried in vain to free himself. As he was about to drown, the elephant-king picked up a lotus with his trunk. Lifting it towards the heavens, he cried, "I offer this to Vishnu, my lord, the refuge of the helpless." Instantly, Vishnu descended from Vaikuntha and liberated Gajendra by striking down the makara with his chakra.
The Bhagavata Purana narrates the tales of Lord Vishnu and his ten avatars, each of whom must save the world from danger, destroy the wicked and protect the virtuous.