ATHENS — The unicorn had wings.
And when a 3-year-old girl climbed aboard the inflatable toy at a beach in the town of Antirrio in southern Greece on Monday, the wind grabbed hold of both her and the flotation device before her parents could react. Within moments, she was carried out to sea, adrift and alone, clinging to the unicorn’s neck.
That was when Grigoris Karnesis, a veteran Greek ferryboat captain, spotted the child.
At first, he couldn’t believe what he was seeing. She was so small, and the toy she was floating on moving so fast, that he barely had time to think.
Mr. Karnesis, the 50-year-old captain of the Salaminomachos, raced to bring his 331-foot-long ferry alongside the toy and rescue the girl. As he drew closer, the ferry’s crew could hear her screams.
He had to steer the hulking vessel — which can hold more than 300 cars and 500 passengers — close enough to the child for someone to grab her without risking toppling the inflatable unicorn. The captain also had to keep the unicorn from getting caught up in the backwash of the ship’s engine. He cut the front engine and worked to “create a lake,” as he described it, around the ferry.
As he steered, the ramp used to load cars onto the ferry was lowered and his brother Vasilis Karnesis, the ship mechanic, scooted to the edge of the platform and snatched the girl from the sea.
“There was nothing this child could do,” he said when reached by telephone.
The rescue was captured on video by a passenger, Petros Kritsonis, 45, who posted it online on Monday. It quickly caused a sensation, and Prime Minister Kyriakos Mitsotakis called the captain to thank him and his crew.
While Mr. Kritsonis said he had posted the video “to show the danger of the sea toys we all use extensively,” social media quickly filled with comments from people casting blame on the parents. The family has declined requests for interviews and could not be reached on Friday, and Mr. Karnesis said the criticisms were unfair.
“We don’t know what can happen from one moment to the next,” he said. “The sea is a deceitful thing.”
While some media accounts said the girl was 4 years old, Mr. Karnesis said that she was just 3 and that he had been shocked to see the small child clinging to the inflatable toy as it sailed hundreds of yards out to sea. A father of two children himself, he said that if he had not returned the girl safely to her parents, he would not have been able to face his own family.
He said the girl’s family had told him that when the unicorn first started to drift from the beach, the girl’s father had raced to catch her, as did others at the beach. People on the beach grabbed a nearby dinghy and tried to row out to her but were caught in the strong current.
When the Greek authorities were notified, they reached out to Mr. Karnesis’s vessel because it was the closest to the scene. The captain estimated that she had been floating for about 20 minutes.
When the girl was finally pulled to safety, she was overwhelmed by what had happened.
“She was in shock, she didn’t speak, she was frozen,” said Mr. Kritsonis, the passenger who filmed the rescue.
She was soon reunited with her distraught mother, who was also speechless.
“We just did what we had to do,” said Vasilis Karnesis, the ship mechanic. In his 22 years at sea, he said, this was the first time he had had to deal with the rescue of a child.
“The next day,” he said, “we felt proud.”