Dhruvaloka, the abode of Lord Viṣṇu within this universe, is situated 1,300,000 yojanas from the seven stars. In the planetary system of Dhruvaloka are the planets of the fire-god, Indra, Prajāpati, Kaśyapa and Dharma, all of whom are very respectful to the great devotee Dhruva, who lives on the polestar. Like bulls yoked to a central pivot, all the planetary systems revolve around Dhruvaloka, impelled by eternal time. Those who worship the virāṭ-puruṣa, the universal form of the Lord, conceive of this entire rotating system of planets as an animal known as śiśumāra. This imaginary śiśumāra is another form of the Lord. The head of the śiśumāra form is downward, and its body appears like that of a coiled snake. On the end of its tail is Dhruvaloka, on the body of the tail are Prajāpati, Agni, Indra and Dharma, and on the root of the tail are Dhātā and Vidhātā. On its waist are the seven great sages. The entire body of the śiśumāra faces toward its right and appears like a coil of stars. On the right side of this coil are the fourteen prominent stars from Abhijit to Punarvasu, and on the left side are the fourteen prominent stars from Puṣyā to Uttarāṣāḍhā. The stars known as Punarvasu and Puṣyā are on the right and left hips of the śiśumāra, and the stars known as Ārdrā and Aśleṣā are on the right and left feet of the śiśumāra. Other stars are also fixed on different sides of the Śiśumāra planetary system according to the calculations of Vedic astronomers. To concentrate their minds, yogīs worship the Śiśumāra planetary system, which is technically known as the kuṇḍalini-cakra.
The Lord fulfilled all Dhruva Mahārāja's desires. His revengeful attitude towards his stepmother and stepbrother was satisfied, his desire for a more exalted position than that of his great-grandfather was also fulfilled, and at the same time, his eternal position in Dhruvaloka was fixed. Although Dhruva Mahārāja's achievement of an eternal planet was not conceived of by him, Kṛṣṇa thought, "What will Dhruva do with an exalted position within this material world?" Therefore He gave Dhruva the opportunity to rule this material world for thirty-six thousand years with unchangeable senses and the chance to perform many great sacrifices and thus become the most reputed king within this material world. And, after finishing with all this material enjoyment, Dhruva would be promoted to the spiritual world, which includes the Dhruvaloka.
But Kṛṣṇa is so kind, He gave him both, that "Dhruva, you desired for some material prosperity, a kingdom. So I have created one kingdom, Dhruvaloka, for you, which is so many times bigger than your father's kingdom. So you will... So that is especially for you. That is Vaikuṇṭha. You will go there. But you wanted your father's kingdom. So you take your father's kingdom also." So he enjoyed his father's kingdom for 35,000 years. In those days, a man used to live for 100,000's of years. Satya-yuga. So Kṛṣṇa is so kind that whatever desires you have got within, He'll give you all facilities. Akāmaḥ sarva-kāmo vā mokṣa-kāma udāra-dhīḥ (SB 2.3.10). But intelligent persons, they will not ask anything from Kṛṣṇa. Just like a dependent child, he's fully dependent on the father. So father knows how to raise him to be a perfect man. He knows what is his necessities. Similarly, we have to give up to the care of Kṛṣṇa, without any condition. That is perfection of life. That is perfection of life.
Specialized Vaikunta planet ( created by the will of Vasudeva only for Dhuva) though in the material world it is.
As it is vaikunta planet it will not be destroyed at the time of devastation.
So Garbhodakaśāyī Viṣṇu; then next Viṣṇu, the third incarnation, is Kṣīrodakaśāyī Viṣṇu. Within this universe there is a planet near the polestar which is called Kṣīrodakaśāyī planet, and there Lord Viṣṇu in His incarnation of antaryāmi, Supersoul... He is acting as the Supersoul.
read the summary to this also.
SB 4.9.21-21 purport:--
Dhruvaloka, was offered to Mahārāja Dhruva. The specific significance of this planet is that until the entire universe is annihilated this planet will remain, even during the devastation which takes place during the night of Lord Brahmā. There are two kinds of dissolutions, one during the night of Lord Brahmā and one at the end of Lord Brahmā's life. At the end of Brahmā's life, selected personalities go back home, back to Godhead. Dhruva Mahārāja is one of them. The Lord assured Dhruva that he would exist beyond the partial dissolution of this universe. Thus at the end of the complete dissolution, Dhruva Mahārāja would go directly to Vaikuṇṭhaloka, to a spiritual planet in the spiritual sky. Śrīla Viśvanātha Cakravartī Ṭhākura comments in this connection that Dhruvaloka is one of the lokas like Śvetadvīpa, Mathurā and Dvārakā. They are all eternal places in the kingdom of Godhead, which is described in the Bhagavad-gītā (tad dhāma paramam) and in the Vedas (oṁ tad viṣṇoḥ paramaṁ padaṁ sadā paśyanti sūrayaḥ). The words parastāt kalpa-vāsinām, "transcendental to the planets inhabited after the dissolution," refer to the Vaikuṇṭha planets. In other words, Dhruva Mahārāja's promotion to the Vaikuṇṭhalokas was guaranteed by the Supreme Personality of Godhead.
Dhruva Mahārāja regrets that he wanted material opulence and greater prosperity than that of his great-grandfather, Lord Brahmā. His begging from the Lord was like a poor man's asking a great emperor for a few grains of broken rice. The conclusion is that anyone who is engaged in the loving service of the Lord should never ask for material prosperity from the Lord. The awarding of material prosperity simply depends on the stringent rules and regulations of the external energy. Pure devotees ask the Lord only for the privilege of serving Him. This is our real independence. If we want anything else, it is a sign of our misfortune.