Searchers are trying to find a person reported to be in trouble in the water at Glenorchy in Otago.
Emergency services were called to the head of Lake Wakatipu, near the Glenorchy Waterfront Reserve, about 4pm.
A police spokesperson said a helicopter, jet boats and other swimmers were assisting in the search.
Police said the search was expected to continue into the evening, assisted by LandSAR volunteers.
The National Dive Squad will be deployed tomorrow.
It is understood to be the same place, north of Glenorchy Wharf, where 48-year-old Linkin Kisling of Wanaka died last Friday while trying to save his son.
His 10-year-old son survived.
RNZ