Shri Ram had been sitting on the bank of the ocean for 5 days but it did not give way, so he asks Lakshman to give him his bow & arrow because it was no use pleading with someone who was stuck in Mamta or giving Gyan to a greedy man. At that instance the Ocean God took the form of a Brahmin & asked for forgiveness, because the sky, wind, water, fire, earth were all made by the same creator. Only by his grace & permission they can do anything not otherwise. It was against Nature for him to dry up but since it was the wish & command of his Lord, he would make way for the army. The Ocean then tells them about the boon received by Nal & Neel & any stone or rock thrown in by them in the water, will always float & never sink. Saying this, he goes back to his abode.
(The Ocean God tells Shri Ram that "even a stone will float in water if the name of Shri Ram is written over it", Since Nal and Neel are great Engineers, they would be able to construct the bridge very easily)
