Early American notions of sympathy, largely shaped by Adam Smith’s theory of rational self-interest and fellow feeling, undergird the period’s dominant narrative tropes, socio-political philosophies, and economic ideologies. In this dissertation, I argue that investments in sympathy structure two “domestic” cultural ideals on a watery globe. The first ideal is of a seamlessly productive shipboard society. The second ideal is of an essentially familial national order. To advance these ideals, common sailors, women writers, and political policymakers uphold sympathy as a corrective to sea-based geological or cultural unruliness. In other words, each asserts that domestic stability in a transoceanic system may be gained via a perfection of moral feeling. As I show in two sections, these discrete sentimental narratives on land and at sea confirm antebellum domesticity’s oceanic entanglements. My first section highlights a shipboard domestic ideal that results from oceanic labors that power a U.S.-backed oceanic economy. Specifically, isolated vessels’ socio-material structures direct sailors’ bodies towards affectively cohesive labor. In short, proper feeling at sea is a technical skill as well as a social one. In this system, ideal “sentimental seamen” know exactly how to feel, how to labor, and how to describe those feeling labors. Sailors use novel materialist, labor-based sentimental forms to stake their relative claims to this economic and social ideal. Ultimately, sentimental seamen embody the forms of regulated and monetized feeling that structure age of sail vessels as historical and literary spaces. My second section tracks an antebellum domestic ideal that results from the nation’s reliance on oceanic cultures and economies. Namely, landed writers debate the domestic nation’s place in a “family of nations” via competing definitions of the “villain of all nations.” Within these debates, “pirates of sympathy” are maritime subjects whose incompatibility with state power is due to their supposed incapacity for moral feeling. For some, such figures’ removal protects an ideal national family; for others, the pirate embodies the effects of state violence. As I conclude, this figure’s pervasive literary-historical presence reflects the antebellum era’s shifting and conflicting moral compasses, particularly in relation to maritime slavery and its inheritances. In tracking sentimental seamen and pirates of sympathy, I place two “domestic” ideals on a watery globe. One is a model for ideal domestic laborers at sea. The other is a foil for ideal domestic citizens on land. Both of these figures are defined by their relation to interior, domestic attachments that ripple across and within transoceanic space. In turn, the study of sentimental seamen and pirates of sympathy provide a glimpse of a field I am tentatively calling “terraqueous domestic studies.” Overall, this field treats early American domestic interiority and attachment as fashioned by earth and water together.