"There must have been about 100 passengers on board and no ramp or assistance from staff to help people off.
"I reckon there was a gap of about 50cm between the boat and the wharf and Poppy just disappeared from sight and fell straight down into the water.
"I couldn't see what was going on at first but when I heard her big sister screaming I knew something had happened to Poppy. My wife thought she had just watched her youngest fall to her death."
Fortunately, the little girl knew how to swim and quickly popped back to the surface and clung to the side of the wharf.
Poppy was taken to a nearby medical centre where she was treated for a head cut and bruising, and scratches on her back and shoulders.
Andrew, a consultant from from Westmere, Auckland, said he was fuming that he still hadn't had satisfactory answers about what happened from operators 360 Discovery since the mid-January incident.
"This could have had a very different and tragic outcome and I don't want this to happen to any other family," he said.
A spokeswoman for Auckland-based 360 Discoveries told the Herald on Sunday an investigation was under way and that a ramp was not in use because of the tide. "We are glad Poppy is recovering well from her ordeal."
Maritime New Zealand said it was also investigating.