According to "The Ramayana - Ashok K banker" Ram tried to construct a bridge for transportation of monkey army but it gets destroyed in a Tsunami so he seeks teh help of sea creatures which raise itself to form the bridge and the sena walks on it to cross to lanka and later sea creatures submerge in to ocean. later after winning war they steal the pushpak vimana ad fly across the sea and reach ayodhya in a day..
