I have spent quite a bit of time in various bird blinds this spring, watching and photographing waterfowl. On three separate occasions, I had the good fortune to enjoy a ring-side seat as Common Goldeneyes underwent their mating ritual.
It was so interesting to observe! The male would first undergo some ritualized displays in front of the female, including stretching his neck in the air, flipping water with his beak and doing some big leg stretches. When she lowered her head into the water to signal her permission, he would rise up in the water, circle to her back, and climb aboard. Her head would be dipped below the surface for a few seconds, then she would resurface and they would twirl around for about 15 seconds during coitus. The deed done, he would then dismount and swim off, usually shaking his head. She would swim away and take a vigorous bath.
These images are quite heavily cropped, which shows the sequence but has resulted in them being a bit grainy. Enjoy!