The army of vanaras has to cross the sea in order to reach Lanka.
So Rama prays to Varuna, the sea-god, for three days. But Varuna does not answer his prayers. Indignant, the Lord lifts his bow and sends forth arrows like thunderbolts into the sea. The sea-god appears with folded hands before Rama. Varuna suggests that the vanaras construct a bridge across the sea under the supervision of Nala, the son of Viswakarma. The vanaras build the bridge using rocks and trees. Sri Rama, Sugriva and the army thus cross the ocean.