A family member found the children in the sea late Friday night, rescued them, and began CPR, before Auckland's Westpac Rescue Helicopter and St John paramedics arrived from Auckland to stabilise the kids and fly them to hospital.
Grandfather Matt Ngawaka, who spent yesterday waiting for updates from his son, said he was extremely grateful to everyone and was hopeful both children would make a full recovery.
"We would like to thank the ambulance service and the Westpac helicopter crew, those guys are brilliant, especially at night."
He also wanted to thank a local nurse who travelled from the Great Barrier Island to Rangiahua in a little tinny boat in the dark to assist the medical crew.
There are just three or four houses on the island, west of Great Barrier Island near Port Fitzroy, and all travel is by boat.
Those who know the whanau say they were shocked the children ended up in the water, as their parents were "extremely careful" and have a good knowledge of water safety.
