The following is excerpts from the famous epic Ramayana written by Valmiki:

Ravana, the king of Lanka disguised as a sage and abducted Sita. Rama who was the husband of Sita was infuriated and wished to bring back Sita by defeating Ravana. Sita was taken to Lanka, which was separated from mainland India by sea. Since, there were no boats at that time, it was very difficult to cross the sea. Lord Rama used his divine powers to enable the stones to float on water. The vanar sena laid down a bridge of floating stones near Rameshwaram which was used to cross the sea.