Can Oceans/Seas ever achieve perfect calm?

Not while there is a gravitational pull from the moon.

@SeventhSense has the right of it. GA.

And not while there is an atmosphere that is subjected to thermal radiation from the sun, creating convection streams, a.k.a. wind that will create waves.
And not while there is a liquid core creating plate tectonic movement, tremors and volcanic activity under the sea.

Over larger and smaller areas, sure; that happens all the time. Over the whole surface? You’ll never see “the whole surface” anyway, calm or not.

Yes, I have been in the ocean when it was flat as glass.

Now if you are asking if it could be that way everywhere at the same time. Then no.

Not unless the earth discontinues to rotate and the moon ceases to shine.

@john65pennington
And of course the moon doesn’t shine. It’s simply illuminated by the sun.

@ChazMaz – I’m not foolish enough to think that a whole ocean would be able to maintain a calm glass like surface. I was only inquiring on an as far as the eye can sea kinda way.
I’m glad someone has seen this.
Thanks

(The eye can see the sea, kinda.)

@Mat74UK In “as far as the eye can see” kind of way, absolutely yes. I live in Hawaii and have spent a good amount of time in coastal waters. On a nice day with very low wind and no swell, the ocean surface can be glassy. It is beautiful, it is incredible, it is quite an experience. The topography of the bottom of the ocean also plays a role. I was just in West Maui where there is a patch of ocean that is protected on many sides by the islands of Maui, Lanai, and Molokai. I spent several days boating in this area (which is actually a (federally?) protected sanctuary), and most of the days the water was glassy. This actually surprised me as I’m used to chop and winds on the west sides of islands during the winter.

Here is a photo of Waimea Bay on Oahu – it looks like this quite often during the summer unless there is a storm. And this is what it looks like on a winter day.

@lilikoi – you lucky lucky git!
Thanks for you reply.

You’re welcome! Here is a photo of the West Maui area I was talking about – open ocean but not too far from the coast.

@lilikoi – thanks mate!

Not a chance. For one thing, there is the law of gravity w=Gm(1)m(2)/r^2. The value of G is not constant. It varies in the third decimal. Nobody has any idea why. Salt water is denser than fresh water, and salt is delivered in rivers, and rivers flow according to rain cycles, and rain cycles are driven by the sun which also drives wind cycles. So salty rivers push down and wind surges pull water up and it’s all moving. Oh, there’s that thing about the moon, too. So I think it pretty unlikely that even a small amount of water can be calm.