 The Threlfall Walk follows the route of the historic 1894 hydro-electric scheme, along old embankments and through ancient cuttings, to a lookout platform high above the river.Crombies Cave, the longest granite cave in Australia at , can be found in the next small creek, Powers Creek, an easy walk to the south of the Blue Hole.As the creek flows under the fence from the surrounding grazing country, within it begins its journey underground to come out down stream.