According to the Vedas, Varun is said to be the supreme protector of the laws of creation. He warns against the sins and creates disease to punish. He is considered to be the most merciful God.
Varun seems to be one of the most important of the Vedic gods. In pre-Vedic times, he was the supreme lord of the cosmos, the keeper of divine order, the bringer of rain, the enforcer of contracts. He is called omnipotent and omniscient; he is responsible for the Sun to move in the sky, for day and night to stay separate, and for the earth to keep its form; he watches the flight of every bird, is present at every gathering, and knows every thought.
Varun is believed to be one of the life bearing elements of the universe. Out of five elements namely- earth, water, fire, air and ether, water is said to be the image of God Varun. In this sense, he is known as the God of life. He is also said to be Lord of water, destroyer of the demons and protector of the devtas (deities). Varun’s empire is so huge that even Swarg (heaven) which is considered to be huge is very small compared to it. Varun is worshipped by saying that Varun is one of the twelve Adityas (Son) who shines with fourteen hundred rays in the month of Aashadh (nineth month of the Hindu calendar).
In the Vedas, Mitra and Varun are considered to be the King of the entire universe. At the same time, according to the ancient beliefs, Varun is the God who regulates the Kaal-Chakra (wheel of time).
According to the Kaal-Chakra, whenever the universe is to be destroyed and after the destruction, a new universe is to be created, then a Pralaya (deluge) happens. Pralayas (deluges) are supposed to be of many types in which ‘water-deluge’ is considered to be the chief deluge. According to the ancient stories, after the water deluge, Manu the first progenitor of man-kind was saved and he came out as the first man of the new human civilization. Varun is the principal of essence of mercy and noose is his weapon. Varun had given this (moon) very sharp weapon, to Arjun. Varun is rarely depicted in images or paintings, but when it is done he is always in the erect posture of perfection, the Atibhanga posture, with a noose in his hand. He rides a Makara, a fabulous animal with the head and front legs of an antelope and the body and tail of a fish. Best of all, he is supposed to live in a house with a thousand doors, as he is always accessible to man.
Once, Varun kidnapped Som’s daughter. When Saint Uchhathya absorbed all the water, Varun had to return her. Saint Vandi, the president of King Janak’s assembly was the son of Varun.
Varuna – Indian Mythology