Now the monkey chiefs made plans to cross the ocean. Everyone gave their own suggestions. Shri Rama said, “I want to pray to Samudradevta (the god of ocean) to give us passage to cross.” He sat in a meditative pose, facing the sea and prayed to the ocean. For three days he sat and offered prayer to the ocean but to no avail. The ocean did not respond. Now Rama asked Lakshman to fetch a bow and arrow so that he could soak up the sea. Lakshman was very happy to hear this aggressive plan.
Disturbed by Rama’s rage, the God of Ocean appeared before him and begged for forgiveness for ignoring Rama’s prayers. He suggested that they build a bridge to cross and he would help them in their endeavour to do so.
Shri Rama prayed to Shiva and he also suggested building a bridge. He said that Nal and Neel, the two avatars of Vishwakarma (God of Vastu and architecture) were expert in architecture and would help you in this task.
On getting the orders from Shri Rama, Nala and Neel with the help of the monkey army began the work of building the Ram Setu. The monkeys brought enormous stones and rocks and Nala and Neel wrote ‘Rama’ on each of them and put them into the sea. With the name of Rama on them, the rocks did not sink but kept afloat.
In their childhood, Nala and Neel would disturb the Rishis by throwing their pooja vessels into the sea. The Rishis then cursed them that from this day on, whatever you throw into water will not sink. This was another reason the rocks stayed afloat. After a while the bridge that was two yojanas (1 Yojana = 8-10 miles) in width was ready.
Now Rama commanded the army to march. In a short while the Rama sena (army) crossed the bridge and reached Lanka. On reaching the shore of Lanka, Rama set up his camp on the Hill Suvela.
Meanwhile Sita was impatiently awaiting the arrival of Rama to rescue her from her life of turmoil.
Building of Ram Setu, Ramayana – The Epic Story