She was driving home to Tapu on Tuesday at 11.30am when her car slid on a corner on the precarious Thames Coast Road between Fisherman's Rock and Windy Pt, hit rocks and flipped twice before landing upside down in the water.
.Ms Matthewson freed herself from the driver's seat and was going to rescue her daughter when Mr Hughes and Mr Griffin, who had been in separate vehicles travelling towards Thames, took over.
"I needed to get my baby out and I just undid my seatbelt, opened my door and got out of the car.
"I went to go open my baby's door and couldn't get it opened so I started panicking. And then these dudes came running across the water and were so good to me."
The car was half-submerged in the high tide when the men broke the glass and bent the pillar of the window frame down so Mr Griffin could swim under and free the toddler, whose head was only 20cm above the water.
He then cuddled Mikaylah, who was unharmed, and took her back to the shore. She was then wrapped in Mr Hughes' outdoor coat.
They also comforted the traumatised mother - who had a sore foot, torn ligaments in her shoulder and back and a bump on her head - and kept her warm with a polar fleece jumper until emergency services arrived.
"[The baby] was quite fine. She was more distressed from the mother screaming, 'My baby'," Mr Griffin said.
"When I hugged her and spoke to her, she was fine."
Mr Griffin was being driven from his Waiomu home to Auckland by a friend when they saw the car in the water.
"You just do it, you don't even think about it," he said. "Everything goes that fast. All we wanted to do was get the baby out."
Mr Hughes, a Tauranga truck driver, saw the car go out of control on the slippery road and land upside down in the water.
"I wasn't thinking, I jumped straight into it. I did what any other person would do. I jumped in, work boots and all - I was up to my waist in water."
It is the second time Mr Griffin has helped in a rescue effort after a car went into the sea. He was at a similar - though fatal - accident on the "unforgiving road" near Waiomu five years ago.
This week, Mr Griffin continued his trip to Auckland, where he took a ferry to Waiheke Island for work.
He made himself known to the police only yesterday morning when he came home and a friend told him they were asking for him to come forward.
Police are now looking at how they can acknowledge the men's bravery.
To Ms Matthewson, the "wonderful" men deserve any reward.
"I want the people to know how appreciative I am they helped get my daughter out of the car and looked after us ... They're awesome."
Thames Fire Brigade station officer Ken Brokenshire said the men saved the toddler's life.
"I think these guys fill the description of modern-day hero. The toddler was in a car seat in the back and these two brave fellows got her out."
