Duck meditation

The Duck Meditation is about Equanimity.

What is equanimity?

Tara Brach puts it well as "the mindful experience that neither grasps nor resists experience".
It is being the 'observer'.

It is letting go to be - just be - with whatever arises.

It is real peace.

"The Little Duck" poem by Donald C. Babcock captures the essence of equanimity:

Now we are ready to look at something pretty special.
It is a duck riding the ocean a hundred feet beyond the surf.
No, it isn’t a gull.
A gull always has a raucous touch about him.
This is some sort of duck, and he cuddles in the swells.
He isn’t cold, and he is thinking things over.
There is a big heaving in the Atlantic,
And he is part of it.
He looks a bit like a mandarin, or the Lord Buddha meditating under the Bo tree.
But he has hardly enough above the eyes to be a philosopher.
He has poise, however, which is what philosophers must have.
He can rest while the Atlantic heaves, because he rests in the Atlantic.
Probably he doesn’t know how large the ocean is.
And neither do you.
But he realizes it.
And what does he do, I ask you. He sits down in it.
He reposes in the immediate as if it were infinity—which it is.
That is religion, and the duck has it.
He has made himself a part of the boundless, by easing himself into it just where it touches him.

Listen or watch Taara Brach explain the concept of equanimity or read about equanimity and the concept of ApE here.