Srimad Bhagavatam Canto 05, Chapter 16, Text 05

SB 5.16.5

yo vayam dvipah kuvalaya-kamala-kosabhyantara-koso niyuta-yojana-visalah samavartulo yatha puskara-patram.
 
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
The planetary system known as Bhu-mandala resembles a lotus flower, and its seven islands resemble the whorl of that flower. The length and breadth of the island known as Jambudvipa, which is situated in the middle of the whorl, are one million yojanas [eight million miles]. Jambudvipa is round like the leaf of a lotus flower.
Srimad Bhagavatam Canto 05, Chapter 16, Text 04
Srimad Bhagavatam Canto 05, Chapter 16, Text 06