SB 4.17.34
sa vai bhavan atma-vinirmitam jagad
bhutendriyantah-karanatmakam vibho
samsthapayisyann aja mam rasatalad
abhyujjaharambhasa adi-sukarah
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
My dear Lord, You are always unborn. Once, in the form of the original boar, You rescued me from the waters in the bottom of the universe. Through Your own energy You created all the physical elements, the senses and the heart, for the maintenance of the world.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
This refers to the time when Lord Krsna appeared as the supreme boar, Varaha, and rescued the earth, which had been merged in water. The asura Hiranyaksa had dislocated the earth from its orbit and thrown it beneath the waters of the Garbhodaka Ocean. Then the Lord, in the shape of the original boar, rescued the earth.