Trail in Namibia Trail in Namibia

The Duck’s Bottom Effect

Many people imagine that the reflections we see in the water are the same as the image we see above the water, only inverted. But they’re not.

The reflection gives us a different view, a new perspective on the scene on the far side. We see it from a lower vantage point.

Have a look at the photo above. Look closely at the bright lights on land and in the water.

Look carefully at the height of these lights.

On land the light behind the crane is the same height as the two red lights on the building. But very different in the water.

On land the two red lights are much higher than the 4 bright white lights near the water’s edge. But the same height in the water.

In a nutshell: the reflection shows us the scene as we would see if we looked from the water, not what we see from where we stand.

I call this the ‘duck’s bottom effect’. When we look down at a duck that waddles past us, we can’t see its bottom. But if the same duck passes through a puddle, suddenly we see its bottom in the reflection. The water allows us to see things that are invisible with a direct perspective.


You might also enjoy:

Eric Ravilious and the Duck’s Bottom Effect

The Direction Ducks Land

How to Spot Patterns in Calm Water

For more on this and other similar effects see How to Read Water – The Book.


Photo credit: John Pahl