sapta dvīpān sa-sindhūmś ca
sapta sapta girīn atha
lokālokaṁ tathātītya
viveśa su-mahat tamaḥ
sapta - seven; dvīpān - islands; sa - with; sindhūn - their oceans; ca - and; sapta sapta - seven each; girīn - mountains; atha - then; loka-alokam - the mountain range separating light from darkness; tathā - also; atītya - crossing; viveśa - He entered; su-mahat - vast; tamaḥ - darkness.
In Kṛṣṇa, the Supreme Personality of Godhead, Śrīla Prabhupāda notes: “Kṛṣṇa passed over all these planets and reached the covering of the universe. This covering is described in the Śrīmad-Bhāgavatam as great darkness. This material world as a whole is described as dark. In the open space there is sunlight, and therefore it is illuminated, but in the covering, because of the absence of sunlight, it is naturally dark.”