A dolphin swam up to two distressed whales that appeared headed for death in a beach stranding in New Zealand and guided them to safety, witnesses said. The actions of the bottlenose dolphin -- named Moko by residents who said it spends much of its time swimming playfully with humans at the beach -- amazed would-be rescuers and an expert who said they were evidence of the species' friendly nature. The two pygmy sperm whales, a mother and her calf, were found stranded on Mahia Beach, about 500 kilometers (300 miles) northeast of the capital of Wellington, said Conservation Department worker Malcolm Smith. Rescuers worked for more than one hour to get the whales back into the water, only to see them strand themselves four times on a sandbar slightly out to sea. It looked likely the whales would have to be euthanized to prevent them suffering a prolonged death, Smith said. They kept getting disorientated and stranding again," said Smith, who was among the rescuers. "They obviously couldn't find their way back past (the sandbar) to the sea." Along came Moko, who approached the whales and led them 200 meters (yards) along the beach and through a channel out to the open sea. "Moko just came flying through the water and pushed in between us and the whales," Juanita Symes, another rescuer, told The Associated Press. "She got them to head toward the hill, where the channel is. It was an amazing experience. The best day of my life." Smith speculated that Moko responded after hearing the whales' distress calls. "They had arched their backs and were calling to one another, but as soon as the dolphin turned up they submerged into the water and followed her."