Known. Almonds in the jars helped date a Greek hull that had been raised.
Off the north coast of Cyprus, the Kyrenia ship was brought up with a largely whole hull. It is a Greek ship of the Hellenistic age, just under 15 metres long, likely with a crew of four. Hundreds of pottery jars were on board. Thousands of fresh green almonds, found in some of the big jars, were dated with the wood and the pottery. The study says the last voyage most likely falls between 286 and 272 BC.
The page still gives the sinking as a span of years, not one exact year, and it also lists wider spans of about 296 to 271 BC and about 305 to 271 BC.