I got this shot in Liwa, UAE, in a deserted area called The Empty Quarter, where there's nothing but dunes for miles. It was 122 degrees F on my car thermometer, so I only stepped out to shoot when I saw something good from the car. Between 4:30 to 5:00 p.m. is when the light is perfect to show the dune ripples, which was when I found some good ones, so it worked out nicely.
I wasn't aware of this challenge until after I got home, then I started looking through my pics and cropping/rotating a few to see what I could do. I was conflicted about using this shot because I liked the uncropped/rotated version for the free study, but I really liked the surreal look and texture of it, so I went with it. Here's my untilted/lesser cropped version:
Thrilled to get blue for this, thanks to all for the votes and nice comments!!
(effectively tilting an image with no horizon or a recognizable object is not easy. The subtle dizzying effect this image casts validates your achievement. For this and for the warmth and the rough yet soft texture I am (re)titling it "Sensual Sands")