Valmiki Ramayana Yuddha Kanda Sarga 4 Shloka 117
Original Shlokaअग्निचूर्णमिवाविद्धं भास्वराम्बुमहोरगम् । सुरारिविषयं घोरं पाताळविषमं सदा ।।6.4.117।।
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अविद्धम् penetrated, अग्निचूर्णमिव like sparks of fire, भास्वराम्बुमहोरगम्the drops of water in the sea, सदा as though, सुरारिविषयं the domain of snakes, घोरम् terrific, पाताळविषमं like the pataala (underworld)
The sea that was the domain of snakes was shining as though sparks of fire from the sky penetrated the drops of sea water.