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]