Police fear a missing international student may have have fallen into the water at a marine reserve next to Goat Island, north of Auckland.
PhD student Yue Gui, 30, also known as Alice, was last seen at 11pm on Saturday at her home at the Leigh Marine Reserve Faculty operated by Auckland University.
Police believe she may have fallen in the water while carrying out her usual temperature checks on Sunday morning during bad tidal conditions.
Police want to hear from anyone who may have seen Alice, who is described as slim, 5ft 2in tall, with dark hair.
The search, which includes members of the police dive squad, will continue on Tuesday.