Fig. 9. Modeled changes in mechanical work stroke^–1 against drag, buoyancy, inertia (surge acceleration) and all three combined during ascent and horizontal swimming at the bottom (109 m), based on dive parameters for a Brünnich's guillemot (BRGU 13; Figs 3, 6 and 7; Table 1) and drag of a frozen Brünnich's guillemot (Fig. 1A). The depth of neutral buoyancy was estimated as 71 m (Fig. 3A). Values at the bottom were based on an estimated mean speed of 1.76 m s^–1.