Here's the mystery thing! This is a light post, on which the ambient light shines onto a white disk. In the background, just at the bottom of the frame, you can see a few building tops - which are the skyline of Miami. This light post is located on the pool deck of the Radiance of the Seas cruise ship...and it just caught my eye while pulling out of port at dusk. I never quite knew what to do with the picture, so it has sat unprocessed for 8 months - until this challenge gave me an idea!