This article considers the bodily experience of being at sea in the age of sail. Using shipboard diaries written by eight passengers during the high period of free migration to the Australasian colonies, it argues that oceanic journeys disrupted and upended the land-based bodily practices being fashioned in nineteenth-century Britain. At sea, these mechanisms of bodily comportment were rendered fragile and unstable, leaving middle- and working-class bodies alike vulnerable and open to refashioning and reformation. In so doing, it points to the need for scholars to bring together land- and sea-based histories and to historicize and particularize oceanic spaces.