Workmen fixing a broken plank in the wharf on the Fryatt St side of the Steamer Basin called police about 11am after they saw the body in the water below.
The man's hand appeared to be gripping the bottom of a ladder attached to the wharf.
The body was recovered by a police diver about 1.15pm.
The officer in charge of the investigation, Detective Sergeant Brett Roberts, said last night police had not yet formally identified the body.
The cause or circumstances of his death had not been determined and police did not know how long he had been in the water.
The man was well-dressed.
The site where the body had been found was cordoned off yesterday, but was not under police guard.
Several officers working on the investigation had talked to people in the area, Det Sgt Roberts said.
Custhomhouse restaurant staff said they were questioned by police yesterday afternoon about who was in the restaurant on Thursday night, what they were wearing and their age.
Bar staff said the restaurant was quiet and no functions were held that night.
People working at other Fryatt St businesses and on the wharf said they knew nothing about the body.
It is understood the water in the basin was about 6degC yesterday.
A Maritime New Zealand spokesman said depending on their size and fitness, a person who fell into 6degC water had an expected survival time of as little as 30 minutes.
Muscles starting shutting down quickly at that temperature.
A relatively fit person could lose up to half of their muscle strength within 20 minutes, making it difficult to prevent slipping under the water.
