A polarizing filter allows you to:

• – control reflections from non-metallic objects; the surface of the water, window, or glossy coating/painting.
• – prevent glare from interfering with other subjects in the image. It also makes subjects underwater transparent.
• – Enhance color saturation and contrast, especially under a scene of deep blue sky, vivid white clouds, or autumn leaves.

This effect can be reduced or amplified by turning the front element of the filter.