A prisoner, who was attacked in Spike Island Prison, is being treated in a Cork hospital for his injuries.
The incident happened when a fight broke out in the courtyard of the prison between three inmates.
The row was broken up quickly by prison officers on duty at the jail.
However, as a result of the attack one of the prisoners received serious injuries.
He was immediately given medical assistance at the jail and was then taken by boat to the mainland.
When he arrived to shore he was rushed by ambulance to Cork University Hospital under garda escort, where he is currently being treated for his injuries.
Prison authorities and the gardai are expected to carry out an investigation into the circumstances surrounding the fight.