Let us hypothesize for a moment... 'cause krakens are fun
Usually the Krakens were depicted as being bigger than ships, more specifically man-o-wars (Kyle Hill in his video used the Earl of Pembroke, but there were certainly bigger and heavier ships out there). Other times... They'd be the size of islands!
According to swedish author Jacob Wallenberg in the 1781 work Min son på galejan ("My son on the galley"): Kraken, also called the Crab-fish, which is not that huge, for heads and tails counted, he is no larger than our Öland is wide [i.e., less than 16 km]
Most accounts believe kraken sightings were actually just colossal squids, so, let's say that a ~15 km long squid existed...
Using a 4.5 m/495 kg specimen as a reference... As well as the classic formula for the square cube law: ((size of Y/size of X)^3) x (weight of X) = Weight of Y
((15000/4.5)^3) x 495 = 1,833,333,300,000 kg (Class T)
That would be the weight of this supposed 15 km long squid. Seems fitting for an island-sized creature that presumably sank other islands. Using the speed of one of its close relatives, its KE would be 40740700000000 J, or 9.7 Kilotons (Town level), but this would just be like, cruising speed, I bet.
Let's bring it down to the ship-sized kraken for less extraordinary results. Let's say... 80 m long, only a wee bit longer than the largest man-o-war ship. Back to the formula:
((80/4.5)^3) x 495 = 2,781,234.57 kg (Class M)
Given the amount of strength the kraken would need to pull down large ships, this weight makes sense.
Using the previous relative's speed again, its KE would be 61805200 J or 14.7 kg of TNT (Wall level)
This also makes sense, though I imagine if the speed was scaled up as well the results would be way higher.
In the book Tracking Sea Monsters, Bigfoot, and Other Legendary Beasts we're given different stats, but I chose bigger examples. I might play around with these numbers later, at some point.