"Initial inquiries report that the man was talking to two men before he was seen in the water.
"We are asking for those two men and anyone else who has information that may assist Police to contact Auckland City Crime Squad on (09) 302 6557.''
Police said they are still working to understand the circumstances surrounding the incident and what happened before the man ended up in the water.
Authorities have been down at the ferry terminal, on Quay St near Lower Albert St, since the search started.
A photographer at the scene early this morning told the Herald a police rescue boat was searching the area.
Several police officers and an ambulance vehicle were also on standby.
The witness said a security guard said it was understood two men had been in the area when one of them fell into the water.
A Coastguard spokesman said they were not aware of an incident.
A number of Fullers ferry services were disrupted this morning as a result, with services running to and from Waiheke affected.
Anyone with information is urged to call Police, or contact them anonymously on the CrimeStoppers 0800 555 111 hotline..
