The girl, who can not swim, was among three teenagers who were saved from drowning yesterday.
Cullercoats' RNLI lifeboat was sent to reports of children being swept out to sea at South Shields, and on arrival, volunteer crew members could see several teenagers scrambling out of the water and onto the beach.
However, a crewman spotted a person about 700m from the shore, and the 14-year-old girl was brought onto the lifeboat after being found floating just under the surface.
She was conscious but extremely cold, and the crew discovered that she could not swim.
Two other casualties - a girl and a boy, both aged 14 - were still unaccounted for, and several other lifeboats were scrambled to search the area around the piers and South Shields beach.
They were later found to be on the beach and in need of immediate medical attention.
Cullercoats RNLI lifeboat helm Ben Bradshaw said: "The girl we pulled from the water was extremely lucky as she was a long way from the beach and difficult to spot, and if we hadn't already been launching to another less urgent service we may not have reached her in time to save her.
"The south-easterly wind wasn't particularly strong so we think the teenagers had been caught up in a rip current which dragged them out to sea."
Tynemouth RNLI crew member Michael Brown said: "The casualties we picked up from South Shields beach were going into hypothermia and weren't in a good way so we administered casualty care while speeding them to waiting paramedics who took them to hospital."
The incident led to a multi-agency rescue involving RNLI lifeboats from Cullercoats and Tynemouth.
The Cullercoats team were re-tasked by UK Coastguard's Humber Operations Centre at 2.50pm from a service to a broken down boat where the occupants were in no immediate danger to the reports of children being sent out to sea.
Four volunteer crew members were on board.
The first casualty was taken to South Shields ferry landing, where she was transferred to the care of paramedics.
The Cullercoats team, as well as both Tynemouth RNLI inshore and all-weather lifeboats, were then launched to search for the missing teenagers.
Members of Sunderland Coastguard Rescue Team and South Shields Volunteer Life Brigade were also tasked by the Coastguard to assist on shore while a police helicopter also searched the area.
The missing casualties were found as Tynemouth RNLI's inshore lifeboat approached the beach.
The three RNLI crew members beached the lifeboat and started getting the casualties warm and administering oxygen as they were suffering mild hypothermia.
Once stable, they were put in the lifeboat and also taken to South Shields ferry landing to be placed in the care of another paramedic crew and taken to hospital.
Once Cullercoats lifeboat had passed their casualty into the care of paramedics, they were released to tow the broken down boat back into Cullercoats harbour, while the crew of Tynemouth inshore lifeboat returned to station after they also transferred their two casualties to paramedics.
Tynemouth RNLI lifeboat station spokesman Adrian Don said: "These teenagers were extremely lucky but our volunteer crew members training, extensive experience and a bit of good luck averted what could easily have been a tragedy.
"There was a fantastic response from all the agencies involved which included UK Coastguard Humber Operations, Sunderland Coastguard Rescue Team, South Shields Volunteer Life Brigade, Northumbria Police, National Police Aviation Service, North East Ambulance Service and our own RNLI volunteers.
"With the summer approaching we'd recommend anyone heading to the seaside to check out the RNLI's comprehensive guide to staying safe at the beach rnli.org/safety/beach-safety and our guide to staying safe in and around water atrespectthewater.com.
"As we've seen today the sea can be very dangerous and unpredictable so we just want people to be safe while they're having fun at the coast."