Yoshiko Cowell was walking along a footpath by the sea wall when she stopped to throw a stick for her dog. She put the stroller brake on but the front wheel slipped and the pram tumbled.
"My daughter Kotomiyo must have leaned forward and the stroller just tumbled down into the water," she said.
Kotomiyo was trapped under the pram but kept her head out of the knee-high water until her mother jumped in, followed by Dalwood.
Kotomiyo was scratched and frightened after her ordeal but otherwise unharmed.
"We were so thankful to Norman for helping, and then when his car went into the water I felt so bad for him."
Dalwood said his car was "a bit damaged" but he was hoping for the best.