The Sea Horror by Edmond Hamilton

Sunset was flaming red in the west once more when Clinton and Stevens stood together again on the submarine's narrow deck, watching the preparations for its homeward voyage. Behind it floated a bare dozen of other long steel craft, as scarred and battered as itself, flung up and saved like itself by that last great convulsion of the waters -- a dozen only, the last remnant of the mighty fleet of hundreds that had dived to the attack a scant few hours before. Even as they watched, three of those craft were moving away on their own homeward journey, toward the west, toward the sunset, over the waters that were now miraculously calmed and smoothened. Their last rejoicing farewells came faintly over those waters as they went, and then they were passing from sight, dark blots against the brilliance of the western sky, dwindling and vanishing.

There came into the minds of both men, as they gazed across the peaceful waters, a wonder as to what frantic outbursts of joy were shaking the peoples of earth to see those waters calmed thus, to see their terrible rise thus halted. There came into their minds a vision of what might have been, of the seas that might have whelmed a planet, with a strange and terrible race triumphant and supreme upon it, and then one of what would be, when the hordes of fugitives, half hoping, half doubting, would creep back from their hills and mountains of refuge toward their deserted lands and cities, when the places that were silent now and dead would be ringing again with life, when all the terror that had riven earth would be but a thing of the remembered past.