Long ago, evil was on a rise, very little was left of dharma, and every living person (save one called Manu), became corrupt. The actions of men called upon them the wrath of nature, a massive flood, which would engulf in it all the landmass and all life on earth. The preserver god, Vishnu, then took the form of a fish and came to meet the pious Manu and asked him to build a boat and house a pair each of all life-forms on it, which it (fish) would steer to safety in the flood. Manu did as instructed, and from him re-emerged all life on earth, the beginning of a new era.
The above mentioned is a narrative from the Vedic Puranas. Interestingly, the great flood is found in the historical accounts of all cultures and faith across the globe.
Celtic: There was a great flood which killed all humans except a single pair, who were saved in a ship made by a beneficent Titan. [Sproul, pp. 172-173]
Roman: Jupiter was angered evil on earth and with Neptune’s help he sent floods to destroy everything. Deucalion and his wife Pyrrha escaped the flood on a boat and repopulated the world on the advice of an oracle. [Ovid, book 1]
Greek: Zeus sent a flood to destroy the men. Prometheus advised his son Deucalion to build a chest. Deucalion and his wife Pyrrha, after floating in the chest for nine days and nights they reached the shore and repopulated the world. [Apollodorus,1.7.2]
Welsh: The lake of Llion burst, flooding all lands. Dwyfan and Dwyfach escaped in a mastless ship with pairs of every sort of living creature and repopulated the world. [Gaster, pp. 92-93]
Lithuanian: In the wake of injustice on earth, the supreme god Pramzimas sent two giants, Wandu and Wejas (water and wind), to destroy earth. Some people and animals had sought refuge in a nutshell and floated to safety. [Gaster, p. 93]
Sumerian: The god Enlil warned the priest-king Ziusudra of the coming flood and instructed to build a great ship and carry beasts and birds upon it. [Hammerly-Dupuy, p. 56; Heidel, pp. 102-106]
Egypt: Atum said he will destroy all he made and return the earth to the Primordial Water which was its original state. [Faulkner, plate 30]
To Be Continued….