While physics and fluid dynamics might be complex subjects, this experiment is breathtakingly simple. All you need is a plate, some (preferably dark) food coloring and a pool (technically, a large bathtub would work, but you need something a bit larger for effect). Physics Girl has come up with a video explaining the science behind these colorful vortices. It's pretty spectacular. You need to see it for yourself.
A Weird & Wonderful Pool Vortex (Video)
12. 27. 14 by Jaime Trosper