The drugs, which Gardaí (Irish police) said had an estimated street value of €150 million, were seized from a bulk carrier off the coast of County Cork on Wednesday.
In court were Jamie Harbron, 31 years old, of South Avenue, Billingham, Stockton-on-Tees, England and Vitaliy Lapa, 60 years old, of no fixed residence but originally from Ukraine.
Both men appeared at a special hearing at Waterford District Court on Friday night.
Gardaí said the arrest was the largest in the history of the Irish state.
Both men were charged with conspiracy to import drugs. Neither responded when charged. They have been remanded in custody and will appear before Wexford District Court on Monday, via video link.
Two men have been arrested after being taken to safety from a fishing vessel off the Wexford coast after the vessel ran aground on a sandbar on Sunday evening.
They appeared in court following a major ongoing investigation into illegal drug trafficking, which this week focused on the activities of the cargo ship MV Matthew.
The Panama-registered bulk carrier, which left South America last month, was intercepted and escorted to Cork port on Tuesday by a joint Irish task force, comprising gardai, navy, military forestry, tax and customs officers. It is suspected that the ship intended to join the fishing trawler stranded off the Wexford coast.
Five other men also arrested in the operation remain in custody