Skanda Purana 7.20.196

7.20.196

varāhasya mahārṇavapraveśaḥ, antaḥsamudre kramāllokāllokāntaraṃ gacchato varāhasya rasātalaprāptiḥ, hiraṇyākṣāya varāhāgamanaṃ nivedayituṃ sāgarapālasya dānavasya aśmakapuraṃ prati gamanam .

The Boar enters the great ocean; the Boar, going gradually from world to world within the ocean, reaches Rasātala; the ocean-guarding Dānava goes to the city of Aśmakapura to inform Hiraṇyākṣa of the Boar's arrival.