Swimmer's body in Hawkesbury river

The body of a man who disappeared while swimming with friends has been found in the Hawkesbury River northwest of Sydney.

A group of friends were swimming in the river, west of the Windsor Bridge, just before 6pm (AEDT) on Wednesday when the 25-year-old man got into difficulty and went under the water.

His body was found about 10.40pm on Wednesday night in the area he was last seen swimming.

Police will prepare a report for the coroner.

Officers from Hawkesbury Local Area Command, a police helicopter, police divers and other emergency services were involved in the search.

There are not believed to be any suspicious circumstances surrounding the incident.