Derryvree’s wetland record complicates any image of Late Pleistocene Ireland as uniformly barren: its aquatic and tundra plants reveal temporary ecological opportunities between ice advances. Castlepook’s fauna similarly suggests intermittent movement through changing landscapes, while the possible tool-marked reindeer bone keeps human visitation open without demonstrating settlement. Together, these sites show how preservation and context shape what can be inferred from fragmentary evidence. How might future excavations, dating methods, or palaeoenvironmental comparisons best distinguish brief human presence from natural processes in Ireland’s unstable glacial environments and clarify whether favourable habitats formed recurrent pathways or isolated refuges for people and animals?