Derryvree’s beetles and plant remains show that freshwater wetland persisted during a locally ice-free interval, challenging any simple image of MIS 3 Ireland as uniformly frozen or lifeless. Yet the deposit represents one protected basin, accumulated over time, while shifting ice and later erosion may have erased comparable evidence elsewhere. Castlepook similarly broadens the picture through fauna, but cannot supply a single dated ecosystem. How should researchers combine such uneven wetland, cave and glacial archives to judge whether Derryvree-like habitats were isolated refuges or recurring features of Ireland’s MIS 3 regional landscape, and what further evidence would most clarify this?