Brittany Ferries' flagship was diverted to France after running into trouble in bad weather while sailing from Plymouth to Santander in Spain.
The £100m super-ferry carries 2,400 passengers and 650 cars
Coastguards said windows smashed on one deck and cabins flooded when a 40ft (9m) wave and gale force nine winds hit the Pont-Aven in the English Channel.
Passengers were moved to upper decks. Six of the 1,200 on board suffered minor injuries, Brittany Ferries said.
The vessel was diverted to Roscoff in France where passengers disembarked.
Coastguards were alerted to the problems in the early hours of Monday.
Coastguards said they took about a dozen calls from passengers and their relatives who were worried about the £100m vessel.
But Stephen Tuckwell, from Brittany Ferries, said there was no panic on the vessel.
He said: "The captain sounded the alarm and there was no panic.
"Most of the passengers were in restaurant or bar at the time the waves hit, so there were only about 10 or 20 people directly affected."
He added that the passengers who had suffered minor injuries were treated by the ship's doctor.
The 41,000-tonne German-built super-ferry is capable of carrying 2,400 passengers and 650 cars. It went into service in 2004.
The ship will be inspected and repaired by engineers in Roscoff. She is expected to be ready to go back into service by Friday.