This paper presents an account of Reservoir Hole, including a description and survey of the cave and a history of exploration. The geomorphology of the cave is discussed : it demonstrates several phases of development, spanning multiple glacial-interglacial cycles. Initial cave development began when the water table was at, or above, 160 m OD. has fallen in stages to the current level of approx. 26 m OD. Uranium series and palaeomagnetic age data suggest that initial cave development began some time before 700 ka, and that dewatering of the higher parts of the cave took place prior to Marine Isotope Stage 11.