Spanish authorities have unveiled some of the treasure from a frigate that sank more than 200 years ago with more than 500,000 silver coins onboard.

The treasure from the Nuestra Senora de las Mercedes, estimated to be worth around $500 million, was discovered by a United States salvage company in 2007.

The Spanish naval ship, which was sunk by the British navy in 1804, returned to Spain in February after a five-year legal battle with Odyssey, the US treasure-hunting company that hauled it up.

The trove contains hundreds of thousands of coins and artefacts, such as religious images and chests.

Currently in Madrid, it will be taken to the Museum of Subaquatic Archaeology in the south-eastern port of Cartagena to be restored and eventually exhibited, the institution's director Jesus Prieto said.

"No institution or cultural organisation, nationally or internationally, has ever faced a heritage challenge of this depth," he said.

"To suddenly receive 14 tonnes of silver coins and other cultural goods is a challenge."

He said the museum would receive the treasure by the end of the year and that some of it could be lent to other institutions.

Elisa de Cabo from Spain's culture ministry said a permanent exhibition of the treasure would be set up at the museum, but did not say when.

"It is important from an historical and cultural point of view and because of the huge quantity of objects that this shipwreck had," she said.

"In fact it's one of the shipwrecks that had more cargo in it in the whole history."

A "temporary touring exhibition" will be launched around the second quarter of 2013 to show some of the treasure at venues in Spain.

Against conflicting pleas by Odyssey and descendants of the treasure's original owners, a judge in Florida ruled that the treasure belonged to the Spanish state since it was in a Spanish navy ship.

ABC/AFP