Gardner's Gut is an extensive cave system in the Waitomo area of New Zealand. It is located in the Ruakuri Caves & Bush Scenic Reserve, an area that also contains a number of other natural features of note. The reserve is administered by New Zealand's Department of Conservation (DOC). With a length of over 12 km of explored passages, it is New Zealand's 6th largest known cave system, and the largest in the North Island.