Objects Underwater Are Not Darkened/Shaded and Appear in Full Color

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Hello,
I’m making a top-down sailing game with an Ocean Plane that uses the Water4Advanced material.

Any part of an object, or entire objects, that are below the water line, do not appear any darker or shaded than objects above the water line. Here you can see the shipwreck is partially submerged, but appears in full color.

image
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Is there an easy way to fix this?

Thank you