Police have named 77-year-old Whetuki Sam Kopua and 60-year-old Matekino Lucy Burling, both of Owaka, as the people missing in the Catlin area.
A 60-strong search team made up of police, the NZ Rescue Co-ordination Centre, marine SAR and volunteers have been hunting today for the Mr Kopua and Ms Burling, who were meant to return to shore last night.
The boat has been located, but they were not aboard.
Police said a boat had been found today just south of Nugget Point where the teams were searching but did not confirm if it was the missing boat.
"Divers have been in the water searching the area around the board, but nothing has been located," police said in a statement.