Fig. 3. Relationship between above-water height and the maximum speed before exit. Observed data (386 exits in 13 deployments by nine birds are pooled) are represented by closed circles (successful exit) and crosses (failed exit). The solid curve is the theoretical line for initial vertical speed to reach the height, assuming a take-off angle () of 90° (see text for details). If penguins adopt non-vertical body angles, higher swim speeds were needed to obtain the necessary vertical speeds for the height, which are represented by dotted curves for various take-off angles.