The Blue Mountains' sandstone plateau is riddled with slot canyons carved by ancient creeks, and this licensed operator runs small-group trips through a spread of them — Empress Canyon for a first-timer's introduction to abseiling and canyon walking, Butterbox for an intermediate step up, and Claustral, one of the range's classic advanced routes, for those with the fitness and nerve for a full day of swimming, climbing and rope work underground. Groups are capped at four people per guide, kept deliberately small for a landscape where a slip or a misread water level matters. Multi-day training courses run alongside the guided trips, covering beginner and intermediate canyoning skills and canyon rescue medicine for people heading toward self-sufficiency in the sport. As with any canyon operator, trips run around rainfall and water levels rather than a set season. Based ninety minutes from Sydney in the heart of the Blue Mountains, it's a genuine way into a niche, physically demanding side of a national park most visitors only see from a lookout.