A sinkhole measuring 20m in diameter has been found on reserve land in Waihi.
Hauraki District Council chief executive Langley Cavers said the sinkhole was found this morning on a council reserve between the Waihi Rugby Club and the Martha open pit mine.
Cavers said the site, known to be above historic mine workings, was classified as a hazard zone in 2002 and was cordoned off.
"While this is inconvenient, it is within an area where sinkholes could be expected."