The French luxury yacht, Le Ponant, was boarded by Somali pirates in 2008 and the crew held hostage until a $2.15 million ransom
The six men, aged 25 to 50, face life in prison if convicted of kidnapping and theft as part of a gang after they were arrested in a French operation in Somalia after a ransom was paid.
Only one admits to being a pirate, two admit to having been aboard the 88-metre three-master but only to sell goats, cigarettes and the mild narcotic khat. The other three deny ever having set foot on the boat.
Le Ponant left the Seychelles on 30 March, 2008 with 30 crew and no passengers on board, headed for Yemen where they were to take on passengers for a cruise.
On entering the notorious Gulf of Aden on 4 April, the ship was boarded by pirates armed with assault rifles who forced the crew to head for Somalia.
A week later, the ship's owner, shipping giant CMA-CGM, paid a $2.15-million (€1.7-million) ransom, the crew was freed and the pirates fled into the lawless sands of Somalia.
France hunted the pirates through Somalia, eventually intercepting a 4x4 vehicle as it left a village, finding $200,000 and weapons on board.
The car's six Somali passengers were arrested and Le Ponant crew members positively identified them as the pirates, although some crew have since said they are unsure of the hijackers' identities.
A total of 22 Somalis are being held by France in connection with four hostage-taking incidents.
Last year a Paris court jailed five pirates for between four and eight years for hijacking the Carre d'As in the Gulf of Aden in September 2008. A sixth alleged pirate was acquitted.
Prosecutors are appealing those sentences as being too lenient.