Natural locomotion in fluids includes the swimming of fish and microorganisms and the flying of birds and insects. Other creatures employ similar movements on solid and fluid surfaces, e.g. snails, snakes and water striders. Nature has exploited the complex fluid dynamics of time-dependent three-dimensional flows over a wide range of Reynolds numbers to evolve a variety of interesting mechanisms of locomotion. This workshop will focus on the mechanics of these behaviors and the current state of theoretical and experimental work in the field. The scope will cover the dynamics from low to high Reynolds numbers, emphasizing the links between the fluid dynamics and the nature of the evolved mechanisms. The inclusion of movement over solid and fluid surfaces introduces new phenomena involving surface stresses and complex fluid layers.