Police are appealing to holidaymakers who may have witnessed a collision between two jet-skis on a North Island lake to come forward.
The incident happened at Lake Okareka, near Rotorua, on Saturday afternoon.
One of the passengers, a 17-year-old boy, is presumed to have died.
Police say the depth of the water and altitude of the lake is restricting the amount of time its divers can spend underwater looking for him.
Extra divers were brought in on Monday. The Navy dive squad will arrive at the site with sonar equipment when the search resumes on Tuesday morning.
Coastguard vessels, a helicopter and about 20 local boats had earlier taken part in the search.
Detective Sergeant John Wilson says officers are also investigating how the crash happened and want to speak to witnesses.
Some may have been on holiday in the area and have since returned home, he says, in which case they should contact their nearest police station.