filters - How to "NOT" photograph reflections on water

Is there any lens filter or any other technique, that I can use to photograph lakes, oceans or any water source, without the reflections on it?

Every photo of a water source can be seen with a reflection of any objects or the reflection of sky. I just need to capture the lake without any reflections on water.

What is the technique?

Answer

Use a polarizing filter, which will filter out light polarized in a certain direction (turn the filter until the desired effect is achieved).

This works, because reflected light is polarized in the plane of the surface it is reflected from.

Note that the sky's blue is also polarized, you'll see a distinct graduation when you look at different angles to the sun.

Here you can see two pictures i recently shot (smartphone through sunglasses, please don't judge me) to test the effect.

The first picture shows reflections in the water and the window; the polarizer is turned in the wrong direction.

In this picture, the filter is aligned with the reflections from the water, which are greatly reduced.