With the circular polarizer's effect maximized, the reflection on the surface of the water is pretty much gone but the sky is considerably darker.
<a rel="nofollow" class="external text" href="https://www.flickr.com/people/21442511@N08">Daniel Ramirez</a> from Honolulu, USA
CC BY 2.0
<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/danramarch/4574293788/">Shot with Circular Polarizer #2</a>