Fixing a quick release abseil system onto my harness, I slid down the rope from anchors fixed at full stretch beyond the torrent. Below me the black inscrutable depths beckoned beyond the frothing maelstrom where the waterfall plunged into the narrow channel in its headlong rush through Low’s Gully. An icy blast as I dropped into the water, cutting loose from the rope and striking out for shore, towing a second line behind me. In this bottomless channel I must at all costs avoid entanglement with the rope. On the boulder field beyond, I grovelled out and tensioned the rope off. Minutes later, the rest of the team were whooping down this enormous “death slide” or “zip wire” some 100 metres out from the cliff face. A landscape of mosses and ferns, water worn boulders and black pools teeming with frogs, snakes and weird scuttling creatures set between impenetrable jungles: at last, the notorious canyons of Low’s Gully were yielding up some of their secrets.