They decided to venture further into the harbour, so they swam up past Te Papa and Matapihi toward Maungatapu. Once there, they found the water getting shallower, so they decided to return to deeper water. However, instead of swimming back out through the entrance, they turned and headed into the Rangataua arm of the harbour between Matapihi and Maungatapu.

They struggled over the mudflats of Rangataua, trying to find a way back to the open sea. They knew which direction the ocean lay; they could hear the sound of the waves pounding on to the beach at Ōmanu and Pāpāmoa. Tired and thirsty, they stopped at Karikari on the eastern shore of Rangataua to drink from a spring. They did not know that the spring was magic and that drinking from the spring would turn them into stone. They began to drink. Suddenly all life departed from them.

The father whale came in search of his family. He saw that they had turned to stone. He too, drank from the spring and became fixed behind the mother and baby whale, and is known as Kōpūkairoa. The mother whale, Mangatawa, lies at the southern end of Rangataua Bay with the baby whale, Hikurangi, nestled beside her.