The coastguard rescue team was tasked to Castlerock following a report of two girls cut off by the tide, one of whom was reported as having been injured.
The lifeguards managed to locate one teenage girl at the base of the cliff, just below the caravan park.
One lifeguard and one crew member from the inshore lifeboat landed on the rocks to assist the stranded girl, who was by that point hypothermic, distressed and exhausted from having tried to swim to safety.
She had also sustained a number of abrasions from making contact with the rocks.
Although the spring tide was rising rapidly, her condition made a rescue by sea very difficult. It was therefore decided to carry out a rope rescue.
A coastguard rope rescue technician descended the cliff and brought the stranded girl to safety, just as the waves broke over the rocky platform where she was stranded.
The teenager was soon reunited at the cliff top with her parents and with her friend, who had managed to swim to safety and had raised the alarm.
Both girls were taken to hospital by ambulance as a precaution against secondary drowning.
The coastguard later found two teenage boys had been with the girls, sustaining lacerations and abrasions as they tried to cross the rocks towards Castlerock beach.
Earlier in the evening, Coleraine Coastguard was tasked to White Rocks in Portrush where a four-year-old boy had sustained a head injury on the rocks.
On arrival it was found that the RNLI lifeguards on duty had assisted the child and delivered him into the care of the NI Ambulance Service.