Vile Paul Trotter, 34, was a kids’ activity supervisor on Cunard luxury liners.
He filmed himself committing the sickening crimes aboard the Queen Elizabeth, Queen Mary 2 and Queen Victoria.
Cops said he preyed on youngsters over seven years in which he went on 295 voyages.
Trotter, of Pontefract, West Yorks, admitted 24 sex offenses involving victims aged between seven and 13 — mostly boys.
They included sexual assaults and making and possessing indecent images of children.
He was remanded in custody at Swindon Crown Court and will be sentenced next month.
Judge Douglas Field ordered Trotter to sign the sex offenders’ register.
After the case, police said cunning Trotter took victims to areas not covered by CCTV where he spanked and molested them. He was caught last August while he was living in Wiltshire.
Officers were tipped off that he had indecent images on his computer and found films of him abusing youngsters.
Horrified Cunard bosses are now working with the NSPCC to tighten up their child protection policies and procedures.
A spokesman said the company was “deeply shocked” by Trotter’s crimes.
Det Insp Nicki Davey, of Wiltshire Police, said a great deal of work went into identifying the children with the co-operation of Cunard.