Divers from Northamptonshire discovered 3,000-year-old artefacts as they explored an old wreck.
The divers were "gobsmacked" by the Bronze Age pieces
The important archaeological find, made public on Tuesday, was made off the coast of Devon by the 12-strong team, half of whom are from Northamptonshire.
The Bronze Age pieces include swords and rapiers, axe heads, an adze, a cauldron handle and a gold bracelet.
The hoard was found as the team explored the site of a 17th century wreck half a mile off Salcombe.
The pieces are being studied at the British Museum where Stuart Needham, curator of European Bronze Age Collections, said it was a very significant discovery.
"It is still extremely rare. Europe-wide there are really only a handful of groups of material of this calibre from the Bronze Age or from pre-history in general," he said.
Experts believe some of the objects are from northern France and the swords are among the earliest found in north-west Europe.
The team is planning to return to the dive site next month
The divers have been exploring south west waters for 15 years and have become involved with the South West Maritime Archaeology Group (SWMAG) who were diving under licence on a shipwreck known as the Salcombe Cannon last summer when they found the hoard.
SWMAG spokesman Christ Yates, of Northampton, said they had been metal detecting for 17th Century artefacts when one of the team found a palstave axe head.
They thought it might be a woodworking tool and were stunned when they learned the truth.
The divers are planning to return to the site with English Heritage next month to see what else is there.