Students from a Dublin secondary school formed a guard of honour on the streets of Ios as the bodies of two teenagers left the Greek island on Tuesday.
Andrew McDonnell and Max Wall, both 18, died within hours of each other over the weekend.
The St Michael’s College pupils were on a trip to the island with fellow students after completing their Leaving Certificate examinations last month.
More than 80 students formed the guard of honour as the bodies began the journey home via ferry and plane.
Post mortems were expected to be carried out on Tuesday in Athens, the Greek capital, after which the bodies will be flown home.
Andrew’s body was discovered at the base of a cliff on Sunday, hours after he was reported missing. Later on Sunday afternoon, it was reported Max had died.
St Michael's principal Tim Kelleher said students placed yellow roses on the hearses as they were transported to the ferry for the journey to Athens.
An investigation is continuing into the deaths of the teenagers.
Tánaiste and Foreign Affairs Minister Micheál Martin said a consular officer was in Ios supporting the students. He said the deaths were "devastating" and "every parent's nightmare".
A book of condolence has been opened at St Michael's College and floral tributes have been laid.
Mr Kelleher said friends and classmates had been traumatised by what had happened.
“Everybody is still coming to terms with this as it’s all so recent,” Mr Kelleher said.
“It was only Sunday afternoon that I got a phone call to say one of the boys had gone missing on the Leaving Cert holiday. Soon after I was notified Andrew’s body had been found at the base of a cliff on very rocky ground.
“The news spread so quickly around the island and here at home. Naturally, when they lost one of their own, the boys are traumatised. They were absolutely hysterical. They are a very tight group of lads, most of them have been in school together since they were four.
“Later then on Sunday afternoon I got a call to say that there may have been a second death among the lads and soon after it was confirmed by his parents. They were making plans to fly out there when I spoke to them, so we had two sets of bereaved parents flying out there.”
Police spokesperson Konstantina Dimoglidou told MailOnline: "While the injuries on [O'Donnell's] neck and head suggest at first glance that he strayed off course; that he tripped and fell, we are also exploring criminal negligence."
The school described Max as "a constant source of positivity" and described Andrew as a "popular" student and a "committed" footballer.
The Ireland Under-20 rugby team, in South Africa for a World Rugby Championship game against Fiji on Tuesday, planned to wear black armbands as a mark of respect to the late teenagers. Several former St Michael's students are in the squad.
There was another tragedy in South Africa after Munster rugby coach Greig Oliver (58) died in a paragliding accident. His son Jack was a member of the squad.
