Det Supt Tanya Jones said a member of the public discovered the body in the Basingstoke Canal at Woodham Lock in West Byfleet on Saturday.
Detectives are treating his death as suspicious. Officers are looking into the circumstances that led to him being found in the water.
Police believe they know who the man is and have informed his family, but have not yet released his name.
Officers want to speak to anyone who was on the towpath, lock bridge or nearby footpaths between Friday night and Saturday morning and who might have heard or seen anything suspicious.
A man's body has been pulled from a canal in Surrey.