Many look to Ireland's Atlantic islands as timeless places, resistant to change. Island Endurance offers an alternative perspective, examining two neighboring islands where people have cultivated their heritage to confront new challenges and opportunities across centuries. To the west, Inishark is a landscape of ruins, with monuments from a medieval monastery alongside the remnants of a village that endured privation and isolation before its evacuation in 1960. To the east, Inishbofin remains home to a small community of nearly 200 that bustles every summer with thousands of visitors drawn by the island's reputation for hospitality and distinctive local heritage. Combining archaeological discoveries with folklore and ethnography, author Ryan Lash explores how islanders from three different historical eras encountered, altered, and reimagined traces of the past. Fifteen years of fieldwork reconstruct more than a millennium of creativity—from the development of pilgrimage traditions at the shrines of monastic saints, to the reuse of medieval monuments for local devotions in the 19th and 20th centuries, to the repurposing of ruins for managing livestock and guiding tourist trails in the 21st century. Attuned to the sensory dynamics and other-than-human elements of landscapes, Lash illustrates the power of quartz pebbles, picnics, and sheep farming to generate vital perceptions of place, time, and belonging. Islanders have continually and creatively adapted their heritage to foster shared experiences, negotiate collaborative relations, and sustain livelihoods amid adversity. Island Endurance shows us that the illusion of timelessness has always relied on the creativity of heritage.