In the meantime, the father of the 14-year-old swam out to help the two girls and managed to get them back to the rocks.
Both RNLI lifeboats, the all-weather Haydn Miller and inshore Georgina Taylor, battled rough seas to reach Morfa Bychan, but fortunately, as they arrived on scene, the casualties just made it to the shore.
The girls, who were from Abergavenny, were met by coastguards and were then treated by paramedics for minor cuts, having climbed over rocks to reach the shore.
The lifeboats carried out a search of the area to make sure nobody else was in trouble before returning to station.