A search has been launched in Bluff Harbour after a member of the public reported seeing two divers swept out in the strong current.
But police say they have conducted a thorough search of the Bluff harbour and Foveaux Strait and did not find anything.
They are yet to confirm if the divers were actually missing.
Police want to speak to the occupants of two white four-wheel drive vehicles that were parked in the vicinity of Marine Parade, Bluff, about 10.30am or 11am today.
"It is believed that occupants from these vehicles were observed entering the water while a third man waited on land," police said.
"We urgently need to speak with the occupants of these vehicles or any person with any information relating to them."
Emergency services were contacted about 1pm by someone who witnessed the divers getting into trouble.
Coastguard, commervcial fishing vessels and a helicopter were involved in the search.
Police also received a report of two people leaving the water in the area and need to confirm if these are the divers earlier reported as being swept out in the current.
There were said to be strong swells in the harbour today, the spokeswoman said.
According to MetService, the region is in for showers today, some heavy with hail. Westerly winds are also expected, strong about the coast.
The coastal forecast for the Foveaux Strait today has westerly winds of 30 knots, easing to 20 knots this evening.
MetService forecasts that the rough seas will ease later in the day.