Dānu, a Hindu primordial goddess, is mentioned in the Rigveda, mother of the Danavas. The word Danu described the primeval waters which this deity perhaps embodied. In the Rigveda (I.32.9), she is identified as the mother of Vrtra, the demonic serpent slain by Indra. In later Hinduism, she becomes the daughter of Daksha and the consort of Kasyapa.
As a word for "rain" or "liquid", dānu is compared to Avestan dānu "river", and further to river names like Don, Danube, Dneiper, Dniestr, etc. There is also a Danu river in Nepal. The "liquid" word is mostly neuter, but appears as feminine in RV 1.54.
As a Hindu goddess, Dānu has 2 temples in Bali, Indonesia: Pura Ulun Danu Temple on Lake Bratan, Bali and Ulun Danu Batur, near Penelokan.
In Balinese cosmology, the Goddess Dewi Danu resides at and rules the lake on the second-highest peak in Bali, Mount Batur. She rules over several hundred subaks (irrigation system), or associations of farmers who share water from a single source, who make pilgrimages to her temple called Pura Ulun Danu, or the Temple of the Lake. There are four lakes in Bali and every lake has their own Pura Ulun Danu.