Starting at the end of April, the service will link Cork and Santander, making two return-sailings a week.
It will be the first time there has ever been a ferry service linking Ireland and Spain.
A new ship will be chartered to serve the route and to deliver an additional weekly return-sailing from Cork to Roscoff.
“This is a significant move for Brittany Ferries, offering haulage companies a direct route to Spain and passengers a far greater range of holiday options from Cork,” said Hugh Bruton, general manager of Brittany Ferries Ireland.
The ship will carry around 500 passengers with space for 195 cars.
Dining options will reflect the Spanish regions served, and there will also be a small shop and café-bar, as well as passenger lounges.
Four-legged members of the family will also be accommodated thanks to a small allocation of pet-friendly cabins on the ship.
Tickets from the new service are expected to be on sale by the end of January.
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