Valmiki Ramayana Yuddha Kanda Sarga 22 Shloka 37
Original Shlokaसबभूवतदाकूपोव्रणइत्येभिविश्रुतः । सततंचोत्थितंतोयंसमुद्रस्येनदृश्यते ।।6.22.37।।
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तदा then, सः that, कूपः well, व्रणःइत्येन as Vrana, विश्रुतः popularly, बभूव came to be known, समुद्रस्येव like the water of the ocean, तईयम् water, सततम् always, उत्थितम् springs out, दृश्यते seen.
That well (hole created by the dart) came to be known as Vrana. The water springing out of it forever is like sea water.