Ecco la notizia nei dettagli:
Lynsey O`Brien, from south Dublin, is feared drowned after she disappeared early yesterday while on a family holiday.
It is understood the 15-year-old was discovered missing from her cabin and the alarm was raised by another family member.
A search of the boat was initiated immediately, but she could not be found.
As news of her disappearance reached classmates at Loreto High School, Beaufort, Rathfarnham, principal Liz Cogan described the situation as "terrible".
"It`s a very difficult time for all of us," Ms Cogan said.
"She was a popular, great youngster, who loved dancing and drama and sports such as basketball."
She said Lynsey, who was in transition year, had a sister in the 5th year and another due to start at the school soon.
"We all know her family very well, it`s terrible," she said.
Students were coming in to the school this morning to offer comfort to Lynsey`s classmates, Ms Cogan said.
A spokeswoman for the Department of Foreign Affairs said Irish Embassy staff in Mexico were offering consular assistance to the family of a girl who had disappeared from the boat.
It later emerged Lynsey`s family had alerted staff on the Costa Magica cruise liner that the teenager had fallen overboard.
Luigi Norsa, a spokesman for Italian company Costa Crociere, which owns the Costa Magica, said a search started as soon as the alarm was raised.
"What we know is yesterday night ... when the ship was around 20 miles from the Mexican coast and around 60 miles from the point of Cozumel, a member of the family of this girl informed the command of the ship that the girl fell overboard.
"The ship immediately started the search and informed the Mexican coast guard and the American coast guard too, and started the search in co-ordination with the Mexican coast guard," he said.
John Phelan, chairman of the Loreto Beaufort parents` association, said there was total shock and utter devastation amongst parents and Lynsey`s friends in transition year.
"Fourth years, transition years, they`re very young women and they`re totally devastated.
"She was a lovely girl, popular, vibrant, typical 15-year-old," he said.
He said the Loreto High School principal and counsellors had been comforting Lynsey`s classmates at the school.