Grim discoveries: three bodies found in two states

Strike force detectives are investigating the deaths of a woman and a visiting family friend at the home she shared with her husband, while in a separate tragedy, the body of a woman has been retrieved from a city waterway.

Police were called to a house on the outskirts of Coffs Harbour on the NSW mid north coast following the discovery of two bodies just after 5pm on Friday.

Local crime manager Detective Inspector Peter O'Reilly said the 61-year-old woman had been identified as having lived at the Boambee residence along with her husband.

The dead man, who was still to be formally identified on Saturday afternoon, was believed to have been aged in his 60s and was visiting the couple, Insp O'Reilly said.

Strike Force Yarnko has been formed to investigate the circumstances surrounding the deaths.

"Local detectives are being assisted by State Crime Command's Homicide Squad and we are appealing to anyone with information they believe relevant to this investigation to contact Coffs Harbour Police," Det Insp O'Reilly said.

"Initial information provided to investigators indicates the deceased man was a family friend who had been staying with the couple only a matter of days.

"While the investigation is very much in its early stages, we have no evidence there is anyone else involved in these deaths; however, we will be keeping an open mind as we progress our inquiries."

Police do not believe there is any threat to the local community in relation to the incident.

A report will be prepared for the information of the coroner.

Inquiries are also continuing into the circumstances surrounding the death of a woman in her 30s in Hobart on Friday.

Police were called after a walker spotted a body in Hobart Rivulet about 4.30pm.

The scene remained closed on Saturday.

Police said they were keeping an open mind as to the cause of death and further investigations would involve a dive team and a door knock of local residents.

The rivulet is part of the River Derwent catchment and flows through and underneath Hobart.