Dunedin City Council parks and cemetery manager Scott MacLean said the holes started appearing in the reserve two weeks ago, which formed part of an area of old coalmine workings.
It was not known what caused the holes to form.
"These holes present a risk to people walking in the area, so we have decided to close the reserve until the cause has been determined and a remedy confirmed.
"Geotechnical investigations will be carried out to assess the risk and whether or not remedial work is needed."
The closed area included most of the reserve, apart from a section of turf at the back and the path from Kennedy Rd to Main Rd.
Mr MacLean said he was unsure how extensive the coal mine workings were.
The work to fix the holes was expected to be completed in a month, weather dependent.
