Peter Trudgill, 43, was walking with family members when he was swept into the water near Stonehaven Harbour in Aberdeenshire at about 3pm on Saturday.
Two members of the public helped a police officer to pull him out.
Mr Trudgill, from the Stonehaven area, was airlifted to Aberdeen Royal Infirmary and died in the early hours of Sunday morning.
Inspector Inness Coull said: "Members of the emergency services faced treacherous conditions and the male had been in the water for some time before he was removed by a police officer and members of the public.
"I would like to thank the members of the public for their assistance."
Aberdeen Coastguard watch manager George Downie said: "We would urge members of the public to be extra careful along the shoreline and to avoid going into the water in bad weather.
"Even in shallow water it is easy to become over powered by the strength of the sea."
A report will be submitted to the procurator fiscal, as with all sudden deaths.