What is the story behind this picture? Here's a Short Thread on That.
This incident appears in 8th Skanda of Bhagavata Purana. There was a Great Mountain Named Trikuta in Kshirasagar. In the Jungle Near that Mountain, There lived an Elephant Named Gajendra with his female Consorts.
One day, while he was on a stroll, he felt thirsty. On searching, they found a Beautiful pond. Gajendra dived into the pond and started Enjoying the cold water. Suddenly a Crocodile caught his leg and Started to Drag him down. This struggle lasted for a 1000yrs.
Even After 1000yrs of constant struggle, Gajendra was unable to free himself from the clutches of crocodile. Sensing his End, Gajendra Prayed to Lord Vishnu.
Lord Vishnu was Pleased with Devotional prayer sang by Gajendra and Reached the spot. When Gajendra saw Lord Vishnu, he plucked a Lotus Flower and Offered it to Lord Vishnu. Then, Lord Vishnu Decapitated the Crocodile and Saved Gajendra. ।। इति श्री।।