The Museum of UnNatural History has a page about the Kraken, of course, a pleasant romp through the history of the mythological creature, but unfortunately it does its part to perpetrate a common misunderstanding about the giant squid: that this poor animal is actually capable of taking on a whale.
Though giant squids are considerably less then a mile and a half across, some are thought to be large enough to wrestle with a whale. On at least three occasions in the 1930's they reportedly attacked a ship. While the squids got the worst of these encounters when they slid into the ship's propellers, the fact that they attacked at all shows that it is possible for these creatures to mistake a vessel for a whale.
Sigh. The first sentence, while technically true, would be more informative if it read "some are mistakenly thought to be large enough to wrestle with a whale." You know what is constantly found in the stomachs of whales? Squid parts. You know what is never, ever found in the stomachs of squid? Whale parts.

And the illogic of the last sentence simply boggles the mind. One can only laugh. 

What was the "attack"? Was the squid simply sighted nearby the ship? Was it curiously exploring the new object with its arms? I find it exceedingly difficult to believe that a squid, no matter how giant, could or would take a bite out of a hard, undelicious ship. Even if it tried, how would the sailors even notice? The mouth is hidden in the midst of all the arms.

Anyway, whales eat squid. It is a unidirectional ecological interaction. Everything I have said about squids not eating humans applies tenfold to whales.