The Central Otago District Council yesterday warned the public about the hole which is about 5m from the 45th Parallel Track.
The 45-minute walking track at the 45th parallel, up the side of the Sugarloaf near Lowburn, was developed by the Cromwell Rotary Club, which now maintains the trail.
It is on council-owned land.
Council parks team leader Ian Mann said Rotary had fenced off the sinkhole after it was discovered on Tuesday night.
The hole was about 1.5m wide and between 5-10m deep and it was near the access over the stile from the Luggate-Cromwell road.
''Obviously it's a significant hazard to the safety of walkers and we want to warn folk to stay on the track and well away from the sinkhole,'' Mr Mann said.
He said further inquiries would be made about the history of the site but there were old mining workings in the area and it could be a mining shaft: ''they're quite a common feature in this area''.
''People need to be vigilant and aware of where they are, especially if they're walking with children or dogs.
The track is safe and if they stay to the track, they'll remain safe.''
An assessment would be made this week on a ''permanent'' solution to the hazard. One option was to place a metal mesh ''cage'' over the hole.
The track was very popular and the council was grateful to the member of the public who raised the alarm about the sink hole, Mr Mann said.
