This lecture is an exploration of the archipelagic island imagination of artist, poet and writer Brenda Chamberlain (1912–71) under the rubric of literary cartography. Part of a wider study of the literary text's 'mapmindedness' – the ways in which imaginative writing accomplishes specifically cartographic 'work' – the paper examines Chamberlain's emotional geographies of the Irish Sea, focusing on her fabling autobiographical account of her residence on Bardsey Island (Ynys Enlli), off the Llyn Peninsula, north Wales: Tide-race (1962). Beginning with two suggestive examples of Chamberlain's composite graphic cartography, which plot an imaginative ethnography and gendered 'zoning' of Bardsey, the paper considers the Irish (specifically Syngian) alignments of her representations of the island self. The visual-verbal Tide-race is then brought into focus as a text powerfully invested in the process of mapping island space by means of layered (and knowing) folktale fantasies, troubled by thwarted desire and terror. The Syngian genetics of the work are revealed. At stake is the need Chamberlain felt, mid-century, to carve out her own space as a woman writer on a 'deluding scrap of rock and turf'. More generally, the paper seeks to accomplish a necessary reterritorialisation of Welsh Writing in English.