A wharf cleaning machine and driver plunged 3m off a wharf into Whangarei Harbour during a night shift.
The driver of the small tractor with a sweeper attached to the front was able to swim clear and was hauled ashore by co-workers about 11.15pm on Monday.
The wharf sweeper was part of C3, which is New Zealand's largest on-wharf logistics company.
In a written statement the company confirmed an incident occurred at their C3 Marsden Point operation where a machine operated by one of their employees went over the wharf into the sea.