Accompanied by an army consisting of the four kinds of forces so persevering in battle, Krishna set out from Dwaraka. And crossing many countries, and mountains, crowned with trees, and pieces of water, and streams, he at last arrived at the country of Matrikavarta (alias Matika). There, Krishna got the intelligence that Salwa was coursing on his car of precious metals near the ocean. Krishna followed in his pursuit.
Having reached the main force, Salwa on his car of costly metals was in the midst of the deep heaving with billows! Salwa challenged Krishna repeatedly to fight. Many arrows discharged from Krishna's bow didn't reach his car. Salwa began to shoot thousand upon thousands of arrows in torrents! He rained shafts upon soldiers. But without thinking of the shafts, Krishna continued the conflict. As that car of costly metals was in the sky (or in ocean?), a full two miles off, it could not be seen by Krishna's troops. They could therefore only remaining on the field of battle look on like spectators in a place of amusement.
Krishna shot arrows at the car, which penetrated into the bodies of the Danavas. Then there arose cries in the car of precious metals from those that were dying of wounds by those sharp arrows, falling into the waters of the mighty ocean. The Danavas deprived of their arms, necks, and wearing the form of Kavandhas, fell, sending up tremendous roars. And as they fell animals living in the waters of the ocean devoured them.
Seeing his soldiers fall, Salwa began to fight with the help of illusion. Then he began to ceaselessly hurl at Krishna, maces, and ploughshares, and winged darts and lances, and javelins, and battle-axes, and swords and arrows blazing like javelins and thunderbolts, and nooses, and broad swords, and bullets from barrels, and shafts, and axes, and rockets. He began the contest with mountain peaks (large boulders?). Then there was darkness and light alternately, and the day was now fair, and now gloomy, and now hot, and now cold. And there was a perfect shower of coals, and ashes, and weapons. Then the dome of heaven blazed as with a hundred suns, and with one hundred moons, and thousands and ten thousands of stars! And then none could ascertain whether it was day or night, or distinguish the points of the horizon. Becoming bewildered, Krishna fixed on my bowstring the weapon called Pragnastra. Having regained, light, Krishna again fought with the enemy! (3,20)
Salwa gives False Intelligence to Krishna
A certain person, having his home in Dwaraka, quickly coming to Krishna's car, addressed him like a friend, delivering to Him a message from Ahuka. He seemed to be one of Ahuka’s followers. Sadly and in a voice choked in sorrow, he said words: "O warrior, Ahuka, the lord of Dwaraka, hath said these words unto thee! O Krishna, hear what thy father’s friend sayeth: in thy absence today Salwa, coming to Dwaraka, hath by main force killed Vasudeva, your father! Therefore, no need of battle any more. Cease, O Krishna! Do thou defend Dwaraka." (3,21)
Disregarding this false information, though temporarily stunned by it, Krishna continued the fight.
Krishna Slays Salwa and Destroys Saubha City
This last part of the war seems to have been fought in an island in the midst of the ocean, Saubha apparently being a city in that island. Salwa's troops made a shower of boulders at Krishna and His army. Krishna managed to destroy those boulders with a weapon resembling a thunderbolt. Salwa's car was out of His visibility, but Krishna launched his Sudarsana chakra. That weapon cleft Salwa in twain, who in that fierce conflict was at the point of hurling a heavy mace. With its energy, it set the foe ablaze.
After that brave warrior was slain, the disheartened Danava women fled in all directions, exclaiming Oh! and Alas! Taking His chariot in front of the town of Saubha, Krishna cheerfully blew his conch and gladdened the hearts of His friends. Beholding their town, high as the peak of the Meru, with its palaces and gateways utterly destroyed and all ablaze, the Danavas fled in fear. Having thus destroyed the town of Saubha and slain Salwa, Krishna returned to the Anarttas and delighted all His friends. (3,22)
Many historians argue that this foe who fought with Krishna in the sky or ocean was not the Salwa of Mritikavarta. Mritikavara was a city, also known as Matika, Martika, Mritikavati, etc. It was the capital of Salwa Kingdom in Rajasthan, situated to the south-west of Madra Kingdom and to the west of Matsya Kingdom, ruled by King Virata. This Salwa came and attacked Dwaraka, to revenge the death of Sisupala and was vanquished by Pradyumna, the son of Vasudeva Krishna. The other enemy was probably an ally of this King Salwa. King Salwa could have prompted this foe to attack Dwaraka from the sea. Krishna might have got this intelligence when he reached Mritikavarta. Then Krishna urgently reached the ocean surrounding Dwaraka, where He fought this naval war. This enemy is certainly a sea-faring Danava and an Asura, probably belonging to another civilization. They might have launched this attack on Dwaraka, from their island close to the Arabian Peninsula. The name Salwa is linked with Arabia, as far as Kuwait.
Pandya's Enmity towards Dvaraka
Sarangadhwaja was the king of the Pandyas. Vasudeva Krishna invaded his country. All his kinsmen fled and his father was slain by Vasudeva Krishna in battle. Obtaining weapons then from Bhishma and Drona, Bhargava Rama and Kripa, King Sarangadhwaja became, in weapons, the equal of Rukmi and Karna and Arjuna and Krishna. He then desired to destroy the city of Dwaraka and subjugate the whole world. Wise friends, however, from desire of doing him good, counseled him against that course. Giving up all thoughts of revenge, he is now ruling his own dominions. (7,23). He later made friendship with Krishna and allied with the Pandavas in the Kurukshetra War.
Dvaraka Sinks into the Ocean
The account of Dvaraka's sinking into the ocean is found in book 16 of the Mahabharata, the Mausala-parvan.
Day by day strong winds blew. Earthen pots showed cracks or broke from no apparent cause. Society became corrupt. The day of the new moon coincided with the thirteenth (and the fourteenth) lunation. The fourteenth lunation has been made the fifteenth by Rahu once more. Such a day had happened at the time of the great battle of Bharatas. (Kurukshetra War), it has once more appeared. After that war, 36 years had passed. The messengers proclaimed at the command of Vasudeva Krishna that the Vrishnis should make a journey to the seacoast for bathing in the sacred waters of the ocean. (16.2)
The Yadavas, then with their wives, proceeded to Prabhasa and took up residence there, each in the temporary habitation that was assigned to him, and all having an abundance of provisions consisting of edibles and drink. The Vrishnis, mixing with wine the food that had been cooked for high-souled brahmanas, gave it away unto monkeys and apes. Those heroes of fierce energy then began their high revels, of which drinking formed the chief feature at Prabhasa. Then a dispute arose between Satyaki and Kritavarman on the wrongs they did in the Kurukshetra War. This dispute turned into a great massacre, in which all the Yadava heroes were slain. (16.3)
Arjuna arrived at Dwaraka and addressed the chief officers, telling them to prepare to leave Dwaraka within 7 days, as Dwaraka was going to sink into the ocean. Krishna's grandson Vajra was chosen as their King to rule at Indraprastha.
Arjuna then proceeded to the place where the Vrishnis were slaughtered. Searching out the bodies of Bala Rama and Vasudeva Krishna, Arjuna caused them to be burnt by persons skilled in that act. On the seventh day, Arjuna evacuated Dwaraka Island. After all the people had set out, the ocean flooded Dvaraka, which still teemed with wealth of every kind. Whatever portion of the ground was passed over, the ocean immediately flooded it over with his waters. Beholding this wonderful sight, the inhabitants of Dvaraka walked faster and faster. (16.7) The Pandavas, on their last journey before death, saw Dwaraka covered by ocean. (17.1)