Srimad-Bhagavatam: Canto 5 - Chapter 1 - Verse 4

Sanskrit:

केचनैतज्ज्योतिरनीकं शिशुमारसंस्थानेन भगवतो वासुदेवस्य योगधारणायामनुवर्णयन्ति ॥ ४ ॥

ITRANS:

kecanaitaj jyotir-anīkaṁ śiśumāra-saṁsthānena bhagavato vāsudevasya yoga-dhāraṇāyām anuvarṇayanti.

Translation:

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.

Purport:

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.