Between 1840 and 1870, nearly three hundred whaling captains’ wives accompanied their husbands at sea aboard New England whaleships. Unlike previous scholarship which has analyzed these women solely within the context of mid-nineteenth century domesticity, this study argues these women effected real and lasting change within their communities and the New England whalefishery. By going to sea with their husbands, women like Mary Brewster, Susan Veeder, and Elizabeth Marble defied longstanding gendered traditions wherein men hunted whales at sea and women supported those efforts ashore. In doing so, they joined the ranks of the sister sailors, a term first created by one of the women featured in this study. Using their personal writings as a point of departure, this study examines the transformative nature of the sister sailors’ experiences at sea, how those experiences contributed to changing perceptions of women within whaling communities, as well as to what extent those experiences were influenced by the social, cultural, and political developments of the mid-nineteenth century. This study challenges current narratives about the sister sailors’ significance in the history of the New England whalefishery, while also introducing new variables of interpretation to the study of nineteenth-century women’s lives and gender norms.