Tourists had been warned to avoid the Express Samina, which was described as a "grime-bucket" and the worst vessel in the Greek domestic ferry fleet.
One of the oldest vessels on the busy holiday and domestic routes from Piraeus to the islands, it had been singled out because of a lack of emergency exits.
Built in 1966, the Samina was originally the French SNCM ferry Corse. It has been operating in Greece since the mid-1980s.
Earlier this year it was sold to Minoan Flying Dolphins/Hellas Ferries for a cut-price £2.25 million, and later renamed and refurbished.
A tourist publication, Greek Island-Hopping, had warned readers against using the ferry because of its age.
The current edition states: "This dreadful boat is arguably the worst Greek ferry afloat. A large grime-bucket with a reputation for running late, she is definitely a boat to be avoided."
However, Minoan Flying Dolphins said yesterday the ship was found seaworthy following a merchant marine inspection last week.