The picture of the swimming pool is supposed to convey two ideas.
The first idea, I hope, is obvious: "Please dive in!" To me, the image looks especially inviting.
There is also a more subtle idea illustrated here. In the picture there are a variety of fractal textures: the water, the clouds, the grass, and the trees. To compute the fractal dimension of a set, one overlays the set with grids of varying degrees of coarseness. The tiles surround the pool are therefore reminiscent of the box-counting definition of fractal dimension.