Hindlimb swimming has evolved several times in birds. However, swimming ability can come at a cost to terrestrial locomotion. Ducks have a range of swimming behaviors, including highly terrestrial species, surface swimmers, and divers. We explored how swimming behavior in ducks relates (1) to hindlimb and pelvic skeletal anatomy across the duck tree and (2) to kinematics during walking, surface swimming, and diving in representative species. We hypothesized that (1) hindlimb and pelvic anatomy of diving ducks would resemble hindlimb swimming specialists like grebes and loons while terrestrial and surface swimming species would resemble galliformes and other non-swimming birds and (2) differences in surface swimming and diving ducks’ kinematics would indicate a tradeoff between diving and walking abilities. While ducks do show differences in hindlimb skeletal anatomy among behavioral groups, only one of the measured traits (lateral cnemial crest size) exhibits the hypothesized pattern, with divers exhibiting larger lateral cnemial crests than surface swimmers and terrestrial species, a structure that is thought to contribute to swimming ability in loons and grebes. Some observed kinematic patterns may indicate advantages in swimming (i.e., faster swimming velocities and longer stride lengths) and greater costs in terrestrial locomotion (i.e., higher body angle and higher stride frequency) for the diving specialists relative to the surface swimmers. Surprisingly all species performed similarly across behaviors. Hindlimb anatomy and kinematics show some variation with swimming ability in closely related species, which may reflect the demands that swimming places on the body. However, that all three species use similar top walking velocities and are capable of diving highlights the versatility of the duck body plan.