Bulmer Cavern is New Zealand's longest cave system, running for 74.3 km (46.2 mi) [1] through Mount Owen in the Tasman region of the northwest South Island. [2] John Patterson discovered the cave on New Year's Day 1984, by dropping a rock down and counting the seconds until it reached the bottom.
Bulmer Cavern was the location of a major cave rescue effort in 1998, when it took 80 cavers several days to extract another caver who had fallen and broken his jaw deep in the cavern. [3]
41°33′30″S 172°31′08″E / 41.5583°S 172.5188°E