"I had my granddaughter and she said, 'I can't touch the ground'," 76-year-old Alistair Kennedy told the Herald.
"That's when I felt the ground slipping away from me and I couldn't swim against the current."
Mr Kennedy and his granddaughter Molly Butler were swept out of their depth while swimming in uncharacteristically strong currents - believed to be caused by yesterday afternoon's king tide - at Bucklands Beach.
Molly's father, Simon, saw the pair were struggling to stay afloat about 10m off the beach and swam out to help them.
"I got my daughter off him and realised I couldn't get out of the deep either," he said. "I was trying to get back to shore but was making no progress whatsoever."
His wife, Christine Butler, who was on the beach, watched in horror with her other children, Lucy, 3, and George, 6, as her father, husband and daughter struggled in the sea, screaming for help.
That call was answered by several people in the area, who rushed to the family's aid.
"Two guys came running," said Mr Butler. "I yelled for more help and others came - the whole beach came down to try to help."
A group of three men and two women brought Molly ashore first before assisting him.
Two of the men were struggling to help Mr Kennedy, so Mr Butler threw a body board to his father-in-law, who clung to it as his rescuers brought him ashore.
"The current was so strong and the beach is so steep that even these guys, who were big guys, were tired and struggling," said Mr Butler.
But by the time the family had began recovering, their rescuers had disappeared.
"We were all in shock and when we tried to look around for them they had all gone away. We just really want to say thank you to them, because it could have been ... We're very fortunate."
The current was deceiving, said Mr Kennedy, who was treated at the scene by St John paramedics.
"It looked so peaceful."
Mr Butler said the king tide had changed the beach's usual currents.
"We swim here all the time and you can tell from the way the boats are facing what the current is doing.
"But today they are facing all different ways. You have got to be really vigilant."
Mother dies in bid to rescue kids
A mother who waded into the sea to try to save her children from a king tide rip lost her own life yesterday after being unable to get back to shore.
The 43-year-old was with a friend and their children early yesterday afternoon, at a northern part of Ruakaka Beach, near the Marsden Pt oil refinery.
The two women went into the water to rescue the children, who got into trouble while swimming, police sergeant Craig Burrows said.
"While trying to get to her children, she started to struggle," he said.
The friend and the children were able to reach the shore, and a tourist who saw the drama went in to rescue the struggling mother.
"By that time she was unconscious," Mr Burrows said. "She was taken up on to the beach, but did not regain consciousness and died."
A resident told the Herald she had spoken to a shocked woman who had seen the incident.
"The kids were in knee-deep water, and then next minute a big wave came in and washed them out a little bit.
"The woman went in and tried to save them, and other people were helping. The lady I was talking to, she grabbed one of the girls ... and got to shore."
The same woman later performed CPR on the unconscious woman on the beach, but she could not be revived.
"They said she had too much water in her lungs. It's extremely sad ..."
Ruakaka volunteer firefighter Colin Turner was among fire crew who also helped administer CPR.
Conditions at the beach were rough at the time, he said.
"With the king tides and the wind blowing in it was quite rough, and there were some rips too.
"She was a pretty rough day today."
