A body has been found after a boat capsized on the Riverton bar on Saturday afternoon.
Police Southland area commander Inspector Mike Bowman said they located the person in the water on Saturday night during a final rescue helicopter sweep of the area.
Two people out of five who were on the boat were recovered alive. One is in Southland Hospital.
"This was a heart-wrenching incident, and we extend our deepest sympathies to the whānau of those involved, who are being supported," Bowman said in a statement on Sunday.
"I would like to commend all staff involved in this incident, they responded swiftly and brought all five people home.
"While this was not the result we were hoping for, we are pleased to have been able to recover two of the occupants alive and be able to play our part in returning the deceased to their loved ones."
Coastguard Riverton skipper Ross McKenzie, who responded to the boat tragedy, said the three who died were locals and were known to the Riverton community.
"Obviously we're a pretty small community and everyone knows everyone.
"It's just heart-wrenching for the families and friends of families of the people involved. They've lived in the area for some time... about 1400 people are resident, so we all know it each other."
Conditions were almost perfect on Saturday afternoon, he said.
"I had a look at the bar probably half an hour before ... the incident and was thinking how flat and calm it was.
"But you can never be too sure on crossing a bar - safety first."
Even the most experienced sailors need to be prepared and wear a life jacket, McKenzie said.
In addition to police, Coastguard staff from Riverton and Bluff, Hato Hone St John, Fire and Emergency New Zealand and Search and Rescue volunteers were involved in the search.