"You were always the light of our school, no one can deny that wonderful buzz you gave to each and every one of us, " wrote one Loreto High School, Beaufort student, where Lynsey, from Terenure, was a transition year student.

"Hon, you have no idea how much you're gonna be missed by every single person who ever knew you, " wrote another.

Others recalled funny moments they had with Lynsey in school; the time a biro burst in her mouth and when she fell off her chair in Spanish class. Innocent reminders of how young they are. "I want you to know that I'll always love you and I'll never forget you, " wrote one grieving friend.

The news of Lynsey's disappearance is said to have reached her friends at home through a text message from her sister. Since then, there has been non-stop activity on her site as her friends get together, sometimes in groups as large as 11, to share their grief.

"Lynz, we're all here thinking of you and remembering how crazy you always were!

We will never forget you and everything about you!" wrote one group of friends.

Lynsey travelled to Florida last week with her family, parents Paul and Sandra, sisters Imelda and Kelly and brother Dean, to join a Caribbean cruise on board the Costa Magica liner.

In the early hours of Thursday morning, the fifth day of the cruise, the teenager is believed to have fallen overboard off the coast of the Yucatan Peninsula, Mexico.

A search operation was launched immediately by the Mexican coastguard and after 12 hours, the Costa Magica carried on to its next destination, Cozumel, where the O'Brien family are believed to have disembarked to await news of the search.

According to Luigi Norsa, a spokesman for Costa Crociere, the Genoa-based company which owns the Costa Magica, the search was continuing yesterday with no developments.

"We give our condolences to the family at this very sad time and we are assisting them in every way we can, " he said. "For the time being, we have no news from the search."

A spokesman from the Department of Foreign Affairs also confirmed that the Irish embassy in Mexico is helping the O'Brien family.

"But as of yet there have been no developments, " he said.

Meanwhile, Lynsey's friends have kept vigil on her web-page which has been viewed 1,770 times since she set it up. Described as "bright, funny and bubbly" by her friends, Lynsey was a popular girl who loved listening to Eminem, playing hockey and going to Wesley at the weekends.

"I remember always seeing you around school, always having a laugh and running up and down the corridor, " was how one acquaintance put it.

Picture messages have also been posted on the site. "I know you loved the colour yellow so I just thought I would draw you a picture, " wrote a friend.

Pink and yellow designs bear the messages: "Miss you Lynz" and "I love you so much". Fifty-four people took the quiz entitled 'How well do you know Lynsey, ' that the teenager made herself for her friends.

"Lynz babes, I'm numb, " wrote a close friend. "I've been crying now for two days straight and I know there will be plenty more tears to come."

Lynsey was last active on her site just six days ago.

"We cannot see you, but you are there. You know that we all love and care for you until the very end. We'll miss you my beautiful friend, " wrote a classmate. "What are we going to do without you?

How are we going to cope?"

questions another.

But under each of the dozens of messages appears the sad truth: 0 replies.

MESSAGES TO LYNSEY

>> We will never EVER forget what a total ledge u were and it won't be the same without u, u were a really special person and wer always so bubbly and friendly.

>> Hey chicks (we know how much you loved that word! ). We wish you were here! We love you so much and not a day will go by that we won't think of you pumpkin (another one of your words! ) we still cant believe your gone, but we'll always talk about your wild antics! it'll be like you never left! you mean so much to us lynz, love all the girls! xx

>> Lynsey. . . didnt kno u dat well hun. . . but wenever i ws talkin to ya i'd feel like iv known yu 4 years coz u were so welcoming and nice and friendly with that massive smile. i jus wanna say hun, dat ur an amazing girl.

>> Everything was normal, everything was great, we heard the news of devastation and heartbreak, Why was it you lynsey why oh why, All our tears are gone we've nothing left to cry, Ill miss everything about you, your smile your face your hair Ill miss the way you showed your love in kindness and in care, Our love for you was put to the test, four simple words lyns, 'your simply the best' xxx

>> Heya lynsey, im in 6th year and i just wanna say that everyone in the year is thinking about you and your family at this time! i never really knew you apart from seeing you around school but you were obviously very popular from reading your other comments . . .youll always be in our hearts and youll never be forgottenR.I.P

>> I just wanna say i am missing u so much its unreal. i am totally devastated, i don't no wat2 do.

there was never ever a person in this whole world who was anything like u.

ur just such a legend and every1 luvs ya SO much (like how can u not? ? ) il always remember how funny u were and how determined u were with basically evrything u did. U put every 1 else b4 urself.