One passenger was rescued by emergency services after being knocked overboard by the waves, he said.
All those on board have now been accounted for after being transported to the Worser Bay Yacht Club by police and coastguard.
Two people - including the captain of the vessel - had been taken to hospital with suspected hypothermia, Mr Miller said.
Passenger David Woodnorth said the ferry nosedived into a wave which punched through the front windows of the vessel, soaking passengers, many of whom suffered cuts and grazes.
Mr Miller said three or four cubic metres of water had flooded into the ferry when it nosedived but he did not think the boat had been in any danger of sinking.
- NZHERALD STAFF, with NZPA