Srimad Bhagavatam Canto 08, Chapter 07, Text 09

SB 8.7.9

tam utthitam viksya kulacalam punah
 samudyata nirmathitum surasurah
dadhara prsthena sa laksa-yojana-
 prastarina dvipa ivaparo mahan
 
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
 
When the demigods and demons saw that Mandara Mountain had been lifted, they were enlivened and encouraged to begin churning again. The mountain rested on the back of the great tortoise, which extended for eight hundred thousand miles like a large island.
Srimad Bhagavatam Canto 08, Chapter 07, Text 08
Srimad Bhagavatam Canto 08, Chapter 07, Text 10