A little girl who was swept out to sea while floating on a giant unicorn inflatable was rescued by a Greek ferry.

The child, who was around four years old, was propelled out into the ocean by strong currents in the Gulf of Corinth off the coast of Antirrio in western Greece, reports local media.

When her parents realised she’d drifted out of sight, they contacted port officials, who in turn radioed the captain of a local ferry on the Rio-Antirrio route.

Video taken by one of the ship’s passengers shows the incredible moment the girl, floating atop the huge rubber ring, comes into view.

“I was approaching the port of Antirio and I was notified by the Port Authority that a child, who I did not expect to be so small, had been swept away by the currents on a nearby beach, which is near the port pier,” Captain Grigoris Karnesis told the Greek City Times.

“She was frozen from fear, because the current was very strong. I put the ship in such a position so as not to affect the small inflatable.

“I placed it in such a way that the ship was not affected by ripples, because if the inflatable sank we would have serious problems.

“We approached slowly and were able to rescue the child.”

Footage shows the ferry cautiously approaching the girl, until they are close enough that a man on the back of the ship can reach out and pick her up.

The rescue “went well”, said Captain Karnesis.

It's not the first time something like this has happened.