Oceans are cool..

[Blakenzy]

Cause things happen in there that make your imagination fly... and scare you a wee bit as well 

http://mysteriousuniverse.org/2014/06/nine-foot-great-white-shark-eaten-by-unknown-sea-creature/

[Perd Hapley]

Giant squid?

[bedlamite]

Giant squid?

Not likely. Cephalopods are cold blooded, whatever ate it had a body temp a lot warmer than the water.

[Ron]

Here be dragons

[Viking]

Cthulhu woke up and decided to have a small snack?

[Hawkmoon]

Nessie escaped the loch.

[AJ Dual]

It's something warm-blooded, which means it's most likely, like 99.9% a mammal.

Sperm whale. I figure if they'll go after giant squid, a shark is a nice compact morsel instead, not all tangly, and able to try and fight back with tentacles and suckers etc.

[RocketMan]

Very odd indeed.  While they have been known to kill great whites, it's probably not an Orca as they don't dive that deep, at least not so far as we know.
Sperm whales are large and carnivorous, and dive that deep, but I doubt they could actually take on a great white.  Looking at their jaw structure makes me think killing great whites is outside of their ability.  As we understand it, large squid is their main diet.
Can anyone think of other possibilities outside the realm of cryptozoology?

[Ben]

It's something warm-blooded, which means it's most likely, like 99.9% a mammal.

Sperm whale. I figure if they'll go after giant squid, a shark is a nice compact morsel instead, not all tangly, and able to try and fight back with tentacles and suckers etc.

Seems like a prime candidate. Another story indicates many recorded ascents and descents. It doesn't mention if ascents were to the surface, nor their frequency. Those data, if ascents were to the surface, would be good indicators.

ETA: It might also have been a much bigger great white. Again, the data would indicate one way or another. If the sensor remained below the surface longer than a sperm whale could hold its breath, then super great white (and I hope he stays where he is) could be the culprit.

[TommyGunn]

Gizmodo’s James Baker highlights Smithsonian‘s story of a tagged nine-foot (2.7m) great white shark whose electronic tag washed up on the beach. When scientists checked the data, they discovered a terrifying sequence of events: the tag had been dragged 1,900 feet (580m) below the surface, then eaten—achieving a 78°F temperature. So this raises a reasonable question: what could possibly eat a nine-foot great white shark?

A 20 foot great white ... AKA megalodon.



Probably an Orca.   

[makattak]

A 20 foot great white ... AKA megalodon.



Probably an Orca.   

20 feet... or bigger.

There was a brief glimpse of a half-open mouth, a cavern big enough to swallow a truck. It was lined with multiple rows of 18-centimeter-long teeth. A wide black eye passed, pure malignancy floating in a pool of red-hot venom. Then there was a long, endless wall of iron-gray flesh rough as sandpaper—darker than the skin of a Great White, some part of him noted—and it was past.

(From a fun little story, "He", from Alan Dean Foster about a Megalodon.)

[RocketMan]

Unlikely to be another great white.  The 78° temperature recorded by the sensor makes that difficult.

[MechAg94]

I keep thinking there has to be missing information here.  I feel like I am watching a show on aliens where they only tell you a few actual facts and invite all sorts of speculation.  If they want to know, do like the guys hunting the giant squids.  Drop a bunch of bait and cameras down deep until they get something. 

[RocketMan]

The solution is easy.  Drop a couple of nuclear depth charges and wait around to see what floats to the surface.

[Andiron]

The solution is easy.  Drop a couple of nuclear depth charges and wait around to see what floats to the surface.

Crocodile Dundee style?

Seems legit.