A former Cunard cruise ship worker admitted carrying out sex attacks on 13 boys while working as a supervisor for a children's activity area.
Paul Trotter, 34, pleaded guilty to a string of sexual assaults and taking, making and possessing indecent images of children, most of whom were under the age of 13 at the time.
The supervisor made films of himself abusing the children in his care on board three cruise ships, operated by Cunard. He also possessed other indecent images of children he had obtained online.
In a statement Cunard, part of the Carnival Corporation group and owners of the Costa Concordia which ran aground earlier this year, said it was "deeply shocked" by Trotter's "appalling crimes".
It added he had avoided detection despite a number of safeguards, including having had his criminal record checked.
Trotter, from Pontefract, West Yorkshire, appeared at Swindon Crown Court, dressed in a suit and purple tie.
He admitted 12 counts of sexual assaulting a child under the age of 13, one count of sexual activity with a child under the age of 13, five counts of taking indecent images of a child, five of making indecent images of a child and one of possessing indecent images of a child.
The offences were committed from November 2007 to August 2011 when he arrested by Wiltshire Police's child abuse investigation unit.
Judge Douglas Field told Trotter, who was living in Wiltshire at the time of his arrest, he would be held in custody to return before the same court on May 11 for sentencing.
He also ordered him to sign the sexual offences register before he was taken back to prison.
Speaking outside court, Cunard president and managing director Peter Shanks said: "We were first made aware of these serious allegations eight months ago by Wiltshire Police and were deeply shocked by what we were told.
"Since then Cunard has provided full support and cooperation to the criminal investigation, and where possible within the constraints of the legal system, to the families involved.
"Our own feelings of shock are secondary to those of the families directly impacted.
"As a parent myself I can clearly understand the emotional pain and anguish they have suffered and endured since they were contacted by the police investigating this case.