Last weekend in Virginia Beach I saw swamp rainbows for the first time.

I was birding at First Landing State Park, one of the last places in town that still has a bald cypress swamp, when I noticed that the water between the trees was colored red, orange, yellow, green, blue and purple. The rainbow colors moved as I walked.

Where I come from in western Pennsylvania, a rainbow on water is a bad thing. It means there’s oil on the water’s surface and it got there because people drilled and spilled. But these swamp rainbows are natural.

The water’s calm surface has a thin film of plant oils and pollen that reflects and refracts light. The resulting rainbows are seen better in winter because the sun is so low.

Last month someone else noticed the rainbows at First Landing and posted a photo on Reddit that went viral and was covered by the BBC.

Click here to see additional photos and read more about rainbows in the swamp.

(photo by Kate St. John)