The body of a woman in her 20s was found at a jetty near View St, Balclutha, in the town's industrial area about 9am, by a person working nearby.
Senior Sergeant Richard Whitmore, of Balclutha, said a postmortem would be carried out today in Dunedin.
Police would not confirm whether or not the death was suspicious.
More than a dozen police staff from Balclutha and Dunedin were involved in the riverbank search or interviewing those working or living in the area.
Police cordoned off a section of the riverbank about 500m long, as officers in blue or white overalls spent the morning and most of the afternoon combing the jetty and surrounding area.
The entrance to the riverbank at the corner of View and Jetty Sts was also cordoned off.
The search on the riverbank wound down late yesterday afternoon, but officers last evening remained at key cordon points.
Snr Sgt Whitmore said police were not able to elaborate on the circumstances surrounding the woman's death, but said the circumstances in which she was found at this stage were "unexplained".
Further police inquiries are under way to formally identify the woman and her next of kin.
The area around the riverside jetty is a popular spot with Balclutha's young people, who use the area for socialising or swimming in the lagoon nearby.
