Apostolos Mangouras, the captain of the tanker, Prestige, was freed from jail after London P&I posted $3.2 million for bail.
Mangouras, 68, has been held in jail in Spain close to three months pending trial on charges of causing pollution and disobeying orders from maritime authorities.
The London Protection and Indemnity Club which insured the Prestige paid the bail voluntarily, saying the Greek captain was a hero who risked his life in an effort to save the ship.