How do auks swim and dive underwater?

Auks (family Alcidae) are unique among the order Charadriiformes for their adaptation to swimming and diving underwater. To navigate the water, they utilize both their wings and their webbed feet.12

When swimming underwater, auks propel themselves using their wings in a half-open position. Their swimming movements are achieved by rotating these wings through a figure-eight configuration, which provides the necessary thrust for aquatic locomotion. While their wings serve as the primary means of propulsion, their webbed feet function as rudders to assist with steering. This dual-use capability allows auks to pursue fish and other prey underwater, while still retaining the ability to fly through the air.132