Valmiki Ramayana Yuddha Kanda Sarga 76 Shloka 83

तयोः those two, पादाभिघातात् by the trampling of their feet, मही earth, निमग्ना sank, अभवत् down, वरुणालयः abode of Varuna (ocean), व्याघूर्णिततरङ्गः rolling waves became, चुक्षुभे agitated.

Then by the trampling of their feet the earth sank down, the abode of Varuna (ocean) was agitated with rolling waves.