The natural world never ceases to amaze us with its beauty and wonder. One such wonder is the rainbow swamp phenomenon, a rare and stunning occurrence that takes place in certain wetland areas around the world. The rainbow effect is created by the reflection of light off a thin film of oil that covers the surface of the water. This oil is produced by the decomposition of organic matter, including the wilting leaves of plants in the swamp. In this paper, we explore the science behind this natural phenomenon.

A couple was walking through the woods of First Landing State Park in early November when they saw a rainbow.

Only this one wasn’t in the sky.

The vivid prism streaked across the swamp.

Turns out, it was Mother Nature working her magic.

In perfect conditions, a pattern of pink, purple, blue and yellow blankets the water’s surface, switched on by the sun’s rays.

“It’s most brilliant once most of the leaves have fallen,” said Jennifer Huggins, the park’s chief ranger of visitor services.

The phenomenon is caused by chemicals released from leaves in the water that reflect different colors of light.

Swamp rainbows can be seen on sunny afternoons when the surface has been mostly undisturbed by wind or rain.

It peaks in November, Huggins said.

Brent Rossen and Allison Goz saw one during their hike on Nov. 4, and Rossen posted a photograph of it on Reddit. It has gotten more than 120,000 upvotes.

First Landing State Park encompasses 2,888 acres and sits atop ancient sand dunes. It’s a combination of bald cypress swamp and maritime forest.

The swamp is a wetland area in between the dune tops. It’s not connected to other sources of water and is completely fed by rain.

Foxes, bobcats and coyotes drink from it. Fish, frogs and turtles live in it.

Swirly strands of Spanish moss hang from the branches of the bald cypress trees, which also live in the freshwater swamp. They lose their leaves in the winter.

And these trees have knees that look like stalagmites with rounded tips. They’re actually extensions of the trees’ roots.

One of the many “knees” you can see at First Landing State Park in Virginia Beach, Nov. 29, 2018. The knees are part of the Bald Cypress trees and grow up from the trees roots acting as support. (L. Todd Spencer)

Many of the park’s trails run alongside the swamp and are accessible from the Shore Drive entrance.