Poe’s story reverts over and over again to “the power of metamorphosis”:

about three years past, there happened to me an event such as never happened before to mortal man — or at least such as no man ever survived to tell of — and the six hours of deadly terror which I then endured have broken me up body and soul. You suppose me a very old man — but I am not. It took less than a single day to change these hairs from a jetty black to white, to weaken my limbs, and to unstring my nerves…

*

As the old man spoke, I became aware of a loud and gradually increasing sound, like the moaning of a vast herd of buffaloes upon an American prairie; and at the same moment I perceived that what seamen term the chopping character of the ocean beneath us, was rapidly changing into a current which set to the eastward. Even while I gazed, this current acquired a monstrous velocity. Each moment added to its speed — to its headlong impetuosity. In five minutes the whole sea, as far as Vurrgh, was lashed into ungovernable fury; but it was between Moskoe and the coast that the main uproar held its sway. Here the vast bed of the waters, seamed and scarred into a thousand conflicting channels, burst suddenly into phrensied convulsion — heaving, boiling, hissing — gyrating in gigantic and innumerable vortices, and all whirling and plunging on to the eastward with a rapidity which water never elsewhere assumes except in precipitous descents.

*

In a few minutes more, there came over the scene another radical alteration. The general surface grew somewhat more smooth, and the whirlpools, one by one, disappeared, while prodigious streaks of foam became apparent where none had been seen before. These streaks, at length, spreading out to a great distance, and entering into combination, took unto themselves the gyratory motion of the subsided vortices, and seemed to form the germ of another more vast. Suddenly — very suddenly — this assumed a distinct and definite existence, in a circle of more than half a mile in diameter. The edge of the whirl was represented by a broad belt of gleaming spray; but no particle of this slipped into the mouth of the terrific funnel, whose interior, as far as the eye could fathom it, was a smooth, shining, and jet-black wall of water, inclined to the horizon at an angle of some forty-five degrees, speeding dizzily round and round with a swaying and sweltering motion, and sending forth to the winds an appalling voice, half shriek, half roar, such as not even the mighty cataract of Niagara ever lifts up in its agony to Heaven.

*

It was on the tenth of July, 18—, a day which the people of this part of the world will never forget — for it was one in which blew the most terrible hurricane that ever came out of the heavens. And yet all the morning, and indeed until late in the afternoon, there was a gentle and steady breeze from the south-west, while the sun shone brightly, so that the oldest seaman among us could not have foreseen what was to follow. (…) In the meantime the breeze that had headed us off fell away, and we were dead becalmed, drifting about in every direction. This state of things, however, did not last long enough to give us time to think about it. In less than a minute the storm was upon us…

*

the seas, which at first had been kept down by the wind, and lay flat and frothing, now got up into absolute mountains. A singular change, too, had come over the heavens.

*

a great change took place in the character of the whirlpool. The slope of the sides of the vast funnel became momently less and less steep. The gyrations of the whirl grew, gradually, less and less violent. By degrees, the froth and the rainbow disappeared, and the bottom of the gulf seemed slowly to uprise. The sky was clear, the winds had gone down, and the full moon was setting radiantly in the west, when I found myself on the surface of the ocean, in full view of the shores of Lofoden, and above the spot where the pool of the Moskoe-strom had been.

*

A boat picked me up — exhausted from fatigue — and (now that the danger was removed) speechless from the memory of its horror. Those who drew me on board were my old mates and dally companions — but they knew me no more than they would have known a traveller from the spirit-land. My hair, which had been raven-black the day before, was as white as you see it now. They say too that the whole expression of my countenance had changed.

*

Changes to the weather, the sea, the heavens, the mariner and the whirlpool itself are radical and precipitous. But the greatest change lies in the reversal of the mariner’s fate in the maelstrom: he somehow finds life in “the inmost recesses of the abyss”. “The power of metamorphosis” envelops and constrains, it seems, even death.