During the pelagic trip on Sunday (10 September 2017), we had great looks at a group of Dall's Porpoises (Phocoenoides dalli) as they swam alongside the boat.
Dall's Porpoises are always fun to watch, but incredibly frustrating to photograph. They're so fast — with swimming speeds up to ~30 knots (!), they're one of the fastest of the small cetaceans — and when they surface, it's usually with a very dramatic splash (often called a "rooster tail"). Mostly I end up with photographs of not much animal and a lot of splash.
Here's an example of a Dall's Porpoise surfacing:
Below, I've zoomed in so you can see different features. Dall's Porpoises are mostly black, so the bright white thoracic panel (coming up the side) stands out. Above that you can see the triangular dorsal fin with a bit of gray frosting at the tip. And note the small dark pectoral fin between the white panel and the head.
Just for fun, and because they create interesting patterns, here are some of my best Dall's Porpoise splashes of the day. [Click on the pictures to see the finer details.]
If you'd like to learn more about Dall's Porpoises, check out these fact sheets from the American Cetacean Society and NOAA.