Regenbogensumpfeffekt (ein natürliches Phänomen)

Taken in my neighborhood swamp. This actually isn’t pollution but a natural phenomenon caused by plant oils from decaying vegetation sitting on the surface and the sunlight hitting just right to create the effect. This happens for a couple months during the winter in small pools after the leaves have fallen and it hasn’t rained for a few days.

https://uisjournal.com/the-phenomenon-of-rainbow-swamps-why-do-they-have-these-colors-the-scientific-explanation/