If I saw something like this in the woods, I would assume that some idiot had dumped old oilcans in the pond. Nope. It's a natural phenomenon.
Years ago, when I was leading swamp walks at Clyde Butcher’s Big Cypress Gallery, I noticed what looked like an oil slick on the surface of the water. One of the swamp walk leaders with much more experience, Jeff Ripple, explained that the natural oils from the cypress cones disbursed once they dropped in the water.Top photo via the Pics subreddit. The quoted text and the photo below are from Florida Hikes.