Dall’s porpoises are not usually seen in Glacier Bay, but occasionally are spotted in Icy Strait, just south of the Park’s boundary. They are one of the fastest marine mammals in the ocean, surpassed only by the killer whale, which is their primary predator. As they rocket through the water, they can often be identified by the “rooster tail” splash that trails the fin on their backs. Here several are seen from the bow of a boat as they appear to effortlessly ride the boat’s bow wave at about 10 knots (11.5 mph or 18.5 kph). Photographer: Sean Neilson