This great machine, consisting of the stars and planets, resembles the form of a sisumara (dolphin) in the water. It is sometimes considered an incarnation of Krsna, Vasudeva. Great yogis meditate upon Vasudeva in this form because it is actually visible

Expressions researched:
"This great machine, consisting of the stars and planets, resembles the form of a śiśumāra" |"in the water. It is sometimes considered an incarnation of Kṛṣṇa, Vāsudeva. Great yogīs meditate upon Vāsudeva in this form because it is actually visible"

Srimad-Bhagavatam

SB Canto 5

Dhruvaloka, or the polestar, is the abode of Lord Viṣṇu within this material world. Upon it there is an ocean of milk, and within that ocean there is an island known as Śvetadvīpa. It is clearly indicated that this planet is situated above the seven planetary systems of the ṛṣis, and because this planet is Viṣṇuloka, it is worshiped by all other planetary systems.

SB 5.23.4, Translation and Purport

This great machine, consisting of the stars and planets, resembles the form of a śiśumāra [dolphin] in the water. It is sometimes considered an incarnation of Kṛṣṇa, Vāsudeva. Great yogīs meditate upon Vāsudeva in this form because it is actually visible.

Transcendentalists such as yogīs whose minds cannot accommodate the form of the Lord prefer to visualize something very great, such as the virāṭ-puruṣa. Therefore some yogīs contemplate this imaginary śiśumāra to be swimming in the sky the way a dolphin swims in water. They meditate upon it as the virāṭ-rūpa, the gigantic form of the Supreme Personality of Godhead.