Set in a former sea cliff on the Limestone Coast, the single ornate chamber of Tantanoola Cave is one of the few show caves in Australia accessible to wheelchairs, its floor sealed and its formations lit to glittering effect. A dolomite cave rather than limestone, it is dense with helictites, straws and flowstone - a 'cave of a thousand crystals' that rewards a slow, close look. Guided tours run through the day and the visit is short and gentle, an easy stop on the drive between Mount Gambier and Millicent. Above, the old cliff line marks where the ocean once reached.