Kay Longstaff, a British woman, had to be rescued by the Croatian Coast Guard after falling off her cruise ship and spending nearly 10 hours treading water in the Adriatic Sea.

"I fell off the back of the Norwegian Star. I was in the water for 10 hours, so these wonderful guys rescued me. I'm very lucky to be alive," Longstaff told HRT shortly after returning to shore.

The forty-six-year-old, who lives in Spain, was immediately treated by medical personnel after being rescued. Lovro Orešković, the captain of the rescue ship, told local media that it was a "miracle" that she had survived.

"On the cruise liner, they thought she didn't survive," Orešković said. "She is clearly fit. She told us she does yoga, and that as she floated in the sea she sang the whole time so that her body temperature wouldn't fall, and to stay awake. We have saved a human life and nothing else compares to it."

The search for Longstaff began at 2:17 am on Sunday after the rescue ship was alerted by the captain of the cruise ship that there was a person overboard, according to a statement from the Croatian Coast Guard. Other ships in the area were also notified, and passenger ships Zadar and Celebrity Constellation participated in the search as well, along with a patrol boat and an airplane.

Longstaff fell from the ship at approximately 11:45 pm Saturday, according to CCTV footage reviewed by the crew of the Norwegian Star. She was eventually spotted 0.8 miles from where she fell overboard at 9:40 am Sunday.

The Norwegian Star was on its way to Venice. "The Coast Guard was notified and a search-and-rescue operation ensued. We are pleased to advise that the guest was found alive, is currently in stable condition, and has been taken ashore in Croatia for further treatment. We are very happy that the individual is now safe and will soon be reunited with friends and family," said a spokesperson for the cruise line.

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It is still unclear how Longstaff fell overboard. New York resident Renee Friedman, who was traveling with her husband, told CNN that she first heard there was a woman overboard at 6:00 am on Sunday when the captain made an announcement.

The passengers were told that the missing woman was being looked for and that the arrival in Venice would be delayed. "The main thing is that tragedy was averted and that she was found alive," Friedman said.