Abstract A Quaternary sedimentary sequence (ca. 600 ka) from a perched lake (Old Lake Coomboo Depression) on the World Heritage-listed coastal sandmass of Fraser Island has been analysed for dry bulk density, carbonised particles, pollen and chemistry. A chronology has been constructed for the organic sediments using a combination of radiocarbon and uranium/thorium disequilibrium analysis. The lake basin is small (ca. 9 ha) with a restricted groundwater catchment, delimited by an aquitard, and minimal surface runoff. It therefore acts as a sensitive raingauge with the perched groundwater-table, and hence the sediment facies deposited within the lake, reacting sensitively to any changes in the water budget. The sequence passes through a series of glacial cycles, demonstrating hydrologic and vegetation change. The record indicates a long-term, three-stage fall in the water-table from lake-full ca. 600 ka to an ephemeral lake in the Holocene, paralleled by a shift in the vegetation composition from predominantly rainforest to sclerophyllous components. The evidence for fire is minimal at the beginning of the record, increases from >350 ka through the sequence culminating at or before the LGM, is low during the LGM and is relatively high during the Holocene. Succession, fire and climatic change, along with the accumulative effect of a series of 100 ka cycles, are believed to have driven the hydrologic and vegetation change and a human factor is not required to explain the record. Within the overall long-term increase in aridity recorded through about six glacial cycles, there appears to be a variation in the ‘dryness’ signal of glacial maxima, suggesting some form of ‘supercycle’ phenomenon. This record complements and extends the information available from some of the oldest pollen-analysed Quaternary lake sequences in Australasia, such as Lynch’s Crater in the Atherton Tableland of north Queensland and Lake George in the Southern Tablelands of New South Wales; and from some of the most sensitive lacustrine/fluvial sedimentary records in the Lake Eyre basin. Signals for major environmental changes recorded in deep sea cores and the loess deposits of China may also be represented in the record. The implications of the Depression record, if further corroborated, are significant in relation to climatic modelling, rainforest survival and faunal extinction.