After spending a day poking around in the Sea of Ghosts near Winterhold, I've come to the following conclusion about the cause of the Great Collapse, ca 4E 122, in which most of Winterhold fell into the sea, sparing the college of Mages.

The destruction wasn't caused by ill-thought-out magical frolicking at the college. Nor was it a far-reaching effect of the fall of Lie Rock or the eruption of Red Mountain.

Friends, I put it to you that Winterhold was eaten away from below by horkers.

It's the only possible explanation. There's no city under the water. There's no evidence that a collapse ever occurred. Or rather, the evidence has clearly been eaten. And the only possible culprits, wallowing around on their (understandably!) fat bellies, are several horkers.

Now, I realize that taxonomists will dispute that horkers are capable of eating solid stone. But really, what else is there for them to eat? It makes sense that in the chilled, lifeless waters, they evolved to devour lifeless stone. And over the course of the years they have clearly eaten the entire city of Winterhold.

Very suspicious, seeing horkers so far from Solstheim.

The Great Collapse of Winterhold happened in 4E 122. That's 79 years before the events of Skyrim. What hasn't rotted away, drifted away, or been recovered, has likely been worn down by the waves and current, and plantlife would have ample opportunity to grow.

The Jarl stole their bukkit.

Skyrim won't stand another war.

Or it was eaten by the horkers.

The horkers are under the Thalmor's thumb. This is a recent development, because in Solstheim they never really cared about anyone in their face (unless they were attacked). However, they now have to feign a territorial attitude in order to eat the nordic establishments.

Winterhold was the first. Gods forbid that the horkers move further inland.

Those big fat things aren't Horkers, this is a http://images.uesp.net/1/15/BM-creature-horker-2.jpg anyone else saying otherwise is WRONG!!!!

Strangely, the Horker is the only redesign I didn't like, hopefully modders are on it already

Of course! It all makes sense! If Horkers are far away from their natural habitat of Solstheim, especially to the north coast of Skyrim where there's a lot of occult rubbish floating around from the college, they would be able to do it. Now it is all sensible.

If nordic ruins can survive intact for 4000 years, Winterhold ought to have some rubble remaining.

Something happened there, the red mountain eruption wouldn't have caused the city to fall after a hundred years and several decades. Though I'd hate to say it the college might actually be respondible for it.

80 years is nowhere near enough time for erosion to remove even miniscule traces of a collapse of one stone building, let alone what is supposed to be a whole "city". Sure some materials would have been moved by currents, but not very far if it was any bigger than say, a dining room table. Besides most of Winterhold fell into a crevasse and the sea there is quite shallow. Furthermore, whom would bother to recover it and where is the evidence it was recovered? I see no attempts at rebuilding and no heaping piles of stone and lumber. Nor do I see plant-life in large enough quantites(they don't even have enough time) to have broken down the stones into smaller pieces.

No I am afraid we have a dire case of Horker deconstruction syndrome. First recorded in the great collapse of the ice near Lake Fjalding on the island of Solstheim in the late 3rd era. Tthe specifics escape me as to the exact date though that is because there is much still in the air about whensoever the Nerevarine decided to visit that frigid Island. Lake Fjalding is known as the native mating grounds of many Horkers. The ice just could not support the constant weight and gyrations of the quite invigorated Tripliothoothus Walrusirus during mating season. There were allusions to some other kind of disturbance breaking the ice but it is all pseudoscientific hogwash. Believe it not. This past occurrence leads me to believe that the Horkers have struck again in this instance. The have a notion to destroy things at the most inopportune times. Tsk, tsk.
~puffs on pipe and raises eyes inquisitively~

Winterhold was destroyed by torrential tidal waves. I could easily see something like that picking up and carrying away most of the debris. Do we have any info about its layout pre-Collapse? Perhaps the city itself was up closer to/surrounding the College, and the shacks that are there are on an outlying area of the original city.

Something that intrigues me is... if it wasn't the College's fault, what could create a constant barrage of tidal waves of that magnitude? It's too long after Red Year and too localized (neither Solitude or Dawnstar complained about the tidal waves, AFAIK).

no an army of mudcrabs chased everyone in their homes and destroyed the city

Vehk son of Vehk requisitioned the missing parts of the town for use in his mighty Vehkship. Specifically, he required several tonnes of magicka-super-saturated rock for use in the vessel's Elk-based artificial intelligence, to replace the KINMUNE femto-adakernel that nigularized eight eras ago after botching an update-job on the drivers for Muatra-support.

(sigh) misinformation about this till persists to this day?

http://www.scienceandthesea.org/index.php?option=com_content&task=view&id=104&Itemid=10 They are bulges caused by the tides ebb and flow. They would be much more likely to carry silt/sand over and bury the ruins than to actually move them and wash them away. Big pieces of stone are big pieces of stone. A Tsunami even of a large magnitude would not carry them away. They are too heavy for the Tsunamis to move much if at all. I live in a place that gets hit by Tsunamis(Hawaii) and have visited a place that was just badly hit by a Tsunami(Japan). I also have studies the subject quite a bit through various Oceanography and geology courses.

Heavy rocky structures would hardly be moved at all if they even did move. Over a period of thousands of thousands of years currents may move large stones but their movement is more likely related to tectonic plate movement than the currents. Smaller things definitely get moved but I have seen waves crash again and again against stone walls that are not maintained and have no mortar at all without long lasting effects. They usually manage to shift a few boulders but that is it, and those are round and will roll..

Preach it, brah.

the impact of the waves caused the roof of a large cavern formed from excessive mage tunneling under winterhold to collapse.

I just had flashbacks to Lands of Lore II: Guardians of Destiny, Bravo, candlethief, bravo.

To be serious for a moment, I go boating in the summer on a lake in Indiana which was formed by flooding a small town in 1800-something. The town is still under the water, easily visible, and people snorkel and dive down there to look at it. It's mostly wooden and it's in Indiana, which is quite a bit warmer than Winterhold.

Also, you'd think in 80 years the jarl (who shouldn't even be old enough to remember the collapse) would have gotten over it and rebuilt.

The Elder Scrolls VI: Horkland

It's inevitable.

Fixed. Oblivion already was made for TES IV...

Horkers can eat stone. Hork means to gobble. It also means to steal and to break.

It seems like a waste of a perfectly good excuse for placing ruins to explore.

The point about the Jarl is one that really bugs me, to be perfectly honest. I can accept the bitterness about the collapse in a first or second generation ruler, but three or four generations later (he doesn't seem that old at all, you're right,) wouldn't make much sense. The jarl of Dawnstar, maybe, but not Winterhold. The bitterness toward the college is understandable, since at some point nords apparently started hating magic (though Tsun's commentary on that is refreshing.) The issue of not rebuilding is more justifiable; Winterhold went into an economic depression, and apparently none of the jarls put much effort into trying to bring it back. They're living in/emo over the past while what survived of the community slowly withers away (see the handful of skeletal cottages.) The two together (mage-hate and lack of any visible effort to make things better) really strike me as 'cutting off the nose to spite the face,' or, maybe more 'flaying the face to spite the nose.' Eh. /end rambling