Lord Vishnu thought for some time. Then he said “The killers of the brahmins and the innocents are none other than the Kalakeyas who are the relatives of the slain Asura Vritra. They are killers and are creatures of the dark. They have taken refuge under the ocean and after they maim and kill the brahmins they hide under the ocean. That is why you are not able to find them.

If you want to prevent further killings, you should get them from under the water. But they may not come out on their own. You need to drain and dry the ocean waters to force them out.”

The Devas were perplexed. They asked Lord Vishnu “How can we drain and dry the ocean?”. To which Vishnu replied “Take the help of Sage Agasthya. If anyone can perform this feat, it is only him.:

The Devas went to Sage Agasthya’s ashram in the southern regions. On seeing all of them coming together, Agasthya asked them what they wanted. They paid their respects to him and reminded Agasthya as to how he has come to the rescue of the innocents in the past like killing of the Asura Vatapi or by tricking the Vindhyas from growing further.

They told him “Respected Sage. In each of these instances, you did what was beneficial to all of humanity. Now we are finding that an unknown enemy is attacking and killing innocent brahmins.  We went to Mahavishnu for his help and advice. He suggested that the Kalakeyas who are behind the killing are coming out at night and attacking the brahmins and hiding under the ocean during the day. Lord Vishnu said that draining the ocean was the solution to force the Kalakeyas out and you were to request you to accomplish this difficult task.”

Sage Agasthya was angered when he heard of the massacre of the innocent brahmins. He was happy to be of help. Sage Agasthya then proceeded towards the ocean accompanied by the Devas, the kshatriyas and the brahmins. All the worlds watched Sage Agasthya going towards the ocean as they wanted to witness this great event.

Sage Agasthya stood at the shore of the churning ocean. Sage Agsthya then addressed the kshatriyas and the Devas. “I am going to drink up the waters of the ocean. You be ready with your weapons to go to war with the Kalakeyas when they come out of the ocean bed.” Sage Agasthya then opened his mouth and drank the entire ocean. The Kalakeyas found that they could not hide under the water any more. In the war that followed, the Devas and kshatriyas managed to kill all the Asuras.
Once the Asuras were killed or maimed, the Devas went to Sage Agasthya and thanked him for this great service. They then requested him to recreate the ocean. Sage Agasthya told them with a smile “Oh, I have digested the waters of the ocean. You will have to create a new one.”. He then left for his home.

The Devas then consulted amongst themselves and then went to Lord Brahma. Brahma, of course knew everything that had transpired. He told the Devas “It will take many eons for the oceans to regain their glory. It will happen at the time of the rule of Bagiratha.” The Devas went back to their world knowing that the ocean bed will be dry and come back to its glory during the reign of Bagiratha.