sapta dvipan sa-sindhums ca

 sapta sapta girin atha

lokalokam tathatitya

 vivesa su-mahat tamah

 

Translation: 

 

The Lord’s chariot passed over the seven islands of the middle universe, each with its ocean and its seven principal mountains. Then it crossed the Lokaloka boundary and entered the vast region of total darkness.

 

Purport: 

 

In Krsna, the Supreme Personality of Godhead, Srila Prabhupada notes: “Krsna passed over all these planets and reached the covering of the universe. This covering is described in the Srimad-Bhagavatam 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.”