Only a small portion of Marble Arch caves is open to the public (by boat), but the fantastic picture of the light on the stalactites reflected in the interior lake is really worth the effort. The caves were explored in detail by French potholer Édouard Martel in the late 19C. If you turn right at the road leaving the caves and drive for less than 2.5km/1mi, you can explore more of Marlbank National Nature Reserve, a wild untamed expanse rich in caves, steep gorges, cliffs and woodland.