The Laghu-bhāgavatāmṛta (Pūrva 2.36-42) gives the following description of the Viṣṇuloka within this universe, quoted from the Viṣṇu-dharmottara: “Above Rudraloka, the planet of Lord Śiva, is the planet called Viṣṇuloka, 400,000 miles in circumference, which is inaccessible to any mortal living being. Above that Viṣṇuloka and east of the Sumeru Hill is a golden island called Mahā-Viṣṇuloka, in the ocean of salt water. Lord Brahmā and other demigods sometimes go there to meet Lord Viṣṇu. Lord Viṣṇu lies there with the goddess of fortune, and it is said that during the four months of the rainy season He enjoys sleeping on that Śeṣa Nāga bed. East of Sumeru is the ocean of milk, in which there is a white city on a white island where the Lord can be seen sitting with His consort, Lakṣmījī, on a throne of Śeṣa. That feature of Viṣṇu also enjoys sleeping during the four months of the rainy season. The Śvetadvīpa in the milk ocean is situated just south of the ocean of salt water. It is calculated that the area of Śvetadvīpa is 200,000 square miles. This transcendentally beautiful island is decorated with desire trees to please Lord Viṣṇu and His consort.” There are references to Śvetadvīpa in the Brahmāṇḍa Purāṇa, Viṣṇu Purāṇa, Mahābhārata and Padma Purāṇa, and there is the following reference in Śrīmad-Bhāgavatam (SB 11.15.18).
śvetadvīpa-patau cittaṁ śuddhe dharma-maye mayi dhārayañ chvetatāṁ yāti ṣaḍ-ūrmi-rahito naraḥ “My dear Uddhava, you may know that My transcendental form of Viṣṇu in Śvetadvīpa is identical with Me in divinity. Anyone who places this Lord of Śvetadvīpa within his heart can surpass the pangs of the six material tribulations: hunger, thirst, birth, death, lamentation and illusion. Thus one can attain his original, transcendental form.”