Gardaí say the 14-year-old girl who was injured at Hook Head last Sunday has died.
Aoife Winterlich from Walkinstown, Dublin, never regained consciousness after hitting her head off rocks as she was swept out to sea.
She died in Crumlin hospital this afternoon.
Aoife was one of four teenagers swept off rocks into very turbulent seas and 4m-high waves. The three other teenagers survived.
An air accident inquiry is currently under way into the events during the helicopter rescue operation.
Aoife had recently joined the 55th South Circular Road Scout Group in Dublin. In her short time with the group she was said to be an enthusiastic and popular member who participated fully in all activities.
Scouting Ireland said everyone in the scouting community across the country is devastated by her death.
It is holding an investigation into what happened on the day.