Since Edmond Malone first scented the presence of the Bermuda pamphlets wafting from its pages back in 1808, The Tempest has been increasingly framed as a play about the European encounter with the "New World." With the advent of post-colonial theory it has become a critical commonplace to regard Caliban's enslavement as a prescient exposé of the "victimization of Third World peoples." Yet Jerry Brotton raises a significant caveat when he claims such readings have spawned a "geographically restrictive view of the play" and exaggerated the scale of English settlement in early seventeenth-century America. Colonialism, however, is not exclusively une entreprise d'outre-mer. A colonial dynamic can also arise within a nation-state when the centre invades the periphery, or an urban elite seizes the communal wilds of the rural poor. If Shakespeare cast one eye across the Atlantic when he drew his servant monster, his gaze also encompassed creatures much closer to home. Specifically, I will argue that the chimera known as Caliban is in part inspired by legends of Lincolnshire fen spirits, and that his plight comments on the displacement of local inhabitants by land reclamation projects. To buttress this argument, the article proposes that Shakespeare drew upon a lost play based on the life of Anglo-Saxon hermit and fen-dweller St Guthlac when writing The Tempest. In this hagiography, a learned hermit travels to a remote island surrounded by fens where he is tormented by misshapen demons and confronted by a murderous servant, but overcomes them with the aid of his supernatural powers. Recovering this lost source will further clarify how The Tempest participates in early modern debates over colonization and religion, as well as the destruction of local wetland ecologies. In the process, the article stakes out a via media for an early modern ecocriticism, balancing its presentist agenda with due attention to the environmental matrix of Shakespeare's England.