The man's body was discovered in the loch on Saturday 14 September, 2002, about 800 yards from the village of Luss.
Strathclyde Police said a £20 bank note found on the man was issued in the Leeds/Manchester area.
A force spokesman said the body had been in the water for two or three days and despite media appeals in Scotland, enquiries have failed to identify the man.
Also found in the man's posession was one house key on a key fob which had the word Gouranga printed on it.
The man was described as white, aged between 35 and 55 years, 5ft 9in tall and of medium build.
He had greying, dirty brown hair and he was unshaven with a short beard.
When found he was wearing a green Canda top, a brown corduroy jacket and dark, short-leg trousers from C&A.
One lace-up, black shoe, size eight or nine, from Marks and Spencer was found along side the body.
A cream coloured canvas reversible hat was also found, with a khaki band on one side and khaki with cream band on the other.
Police said the man had no apparent distinguishing marks or features and that there appeared to be no suspicious circumstances surrounding his death.
They advised anyone with any information about the man to contact them on 01389 822000.