The National Science Foundation is having its annual Science & Engineering Visualization Challenge right now.
Lots of cool stuff, like this visualization of (normally invisible) coral flows:
Corals are far from the passive “living rocks” they are sometimes taken to be. This image reveals the hidden flow generated by small hairs (cilia) covering the surface of the coral, between two coral polyps that are 3 mm apart. Two shots taken 1.5 hours apart are combined into a single image, showing how the coral is able to create a long-lasting whirlpool structure that alters the local environment and enhances the coral’s ability to “breathe.”