At the end of the last kalpa, there was a general destruction and the universe was flooded with water. Vishnu alone slept on this water in his form of Narayana. When it was time for creation to begin, Brahma appeared inside an egg. All the worlds that would be there in the universe and all the beings who would populate these worlds were inside the egg. But before creation could start, the earth had to be created so that living beings might have a place to live in. When the earth was first created, it was full of mountain ranges and these mountains were exceedingly heavy. The upshot of this was that the earth could not bear the weight of these mountains and started to get immersed in the water. She went all the way down to the underworld. The earth started to pray to Vishnu so that she might be saved. Vishnu adopted the form of a gigantic boar (varaha). He entered the water and raised the earth up on his tusks. He laid her to rest on the water, having first levelled out the mountains. This was the story of Vishnu‘s boar incarnation.