(The N in this name is pronounced like 'n' in 'turn'. )
One of the twelve Aadithyas is also named Varuna. Do not confuse between these names.)
Varuna was the Lord of the west direction and Lord of the waters too. He was one of the eight cardinal Lords of the universe. His praises are several in the Vedas.
The bow Gaandeevam comes from Varuna to Arjuna through Agni. Finally, Arjuna threw it into the sea during their renounciation walk, as told by Agni.