Human courtship rituals—if you believe television commercials, anyway—are lame. The guy who kneels down right at the jewelry store counter ("It fits perfectly!" "Well honey, that's because I already had it sized") has nothing on birds who walk on water for each other.
Grebes are diving waterbirds that live in the Americas and Eurasia. To pair off, they follow an elaborate courtship choreography that includes trading bits of food and mimicking each other's motions. In the ritual's conclusion, both birds suddenly haul their ungainly bodies out of the water and run together on its surface. The grace of the birds and the physics of the maneuver both seem impossible.
You can see a pair of Clark's grebes do their courtship dance in this incredible video from the BBC. Jewelry companies, take note: there's no prelude to romance quite like swallowing a live fish.
Image: screen grab from BBC Life: Birds: Partners for Life