Are there giant sea creatures and prehistoric sea monsters that are big enough to sink cruise ships, submarines, or even hovercraft?

Absolutely

Well, the largest known marine animal, the blue whale, is only 30m, at most, long.
So, probably not.

20,000 Leagues Under the Sea about 3:50. Actual giant squid are 18 meters or less than 60 feet. There people that believe there is a Colossal squid maybe twice that size no proof. Doubt the would try sinking a ship.

No proof that there aren’t, no proof that there are,.

Could be.

Hell yeah!

Don’t call them pussies.

Impressive, but not quite it.

Note huge, but still plenty creepy

Sharks in the twilight zone.

There is a prehistoric creature I wanted very much to post, but I can’t remember the name. No matter how I word it, YT searches bring back, you want what?!

Liopleurodon?

It’s often smaller creatures, that cause more problems.
Jellyfish, can get stuck in engines, of large ships.

Barnacles, can destroy a hull.

Birds, can bring down huge planes…

I wager, that it’s possible very large animals, live very deep. But. The chances are slim. The chances, of them coming into contact with surface vessels, or even large submarines, is even less likely.

Most giant sea creatures, both modern and prehistoric, are 20–65’ long. As was mentioned, the Blue whale can get to about 100’. A submarine is 400’ long, give or take. A cruise ship is usually closer to 800–1100’ long. I guess some of these creatures could potentially sink one of these vessels, but probably not. If a Blue whale got up a head of steam and reached ramming speed, it could probably do some damage, but would probably not sink it.

@ragingloli, liopleurodon is in my first clip.

Sea creatures need to eat to live. A 100 ton blue whale needs to eat the equivalent of 4% of it’s body weight every day to survive. It does that by eating about 4 tons of krill every day.
Now let’s scale up a mythical sea creature that is 3 times the length of a blue whale That meas it’s mass would be 3×3x3×100 tons or about 2700 tons. It would need to eat 108 tons of food per day or at least 1 giant blue whales every day. That kind of devastating loss would be noticeable. Also if the creature is going to reproduce it likely needs a mate.

Granted, humans have not explored every square meter of the ocean sea floor but an awful lot has been explored and anything that needs to eat that much can’t simply hang around. It needs to go find food. Surely the tens of thousands of sonar units in place around the planet would have seen it already.

@LuckyGuy the whale has the disadvantage we mammals share in being warm blooded. My guess is that the ratio of body weight percentage that must be consumed daily probably decreases as body mass increases (at least with mammals). There is also the huge disparity in nutrition a carnivore obtains from a comparable mass of a meal consumed by herbivores. Which is why grazing occupies so much time of the herbivores we know.

Intent

Close calls

Real, or fake?

When a shark would rather ride than swim.

Some of these could certainly give it a try.

@stanleybmanly I had to start somewhere. If you have better numbers I’ll take them. I was able to find data for blue whales relatively easily.
Do we know whether the giant theoretical sea creature is warm or cold blooded? Maybe a Godzilla wiki would have some answers.

No. Don’t get me wrong. I’m in no way objecting to your excellent example. I was just flitting off topic and wondering if a cold blooded monster might grow bigger as well as eat less.

@stanleybmanly I wasn’t objecting at all. I firmly believe in the value of peer review.
I had not considered that a cold blooded creature might be even larger. It’s a bigger target for the surveillance sonar to find.