Police were notified later that day that the boat and couple, believed to be from Christchurch, were missing.
Martin said the shoreline of Lake Hauroko, along with the wider Wairauahiri river area, would be searched on Wednesday.
Maritime New Zealand investigators would be also be involved.
Once water levels recede and conditions became more favourable, the Police National Dive Squad would join the search, he said.
Martin appealed for boaties using the lake to contact Invercargill Police on (03) 211-0400 if they saw any debris.
Police said they would like to thank volunteers who have assisted with the search so far, including members of Southland LandSAR, the Volunteer Amateur Radio Emergency Communications Group, and the Fiordland Water Rescue Group.
- Otago Daily Times