It is illegal to move or use any boat with an internal ballast tank or bladder outside the controlled zone of the Waikato River unless it complies with specific biosecurity restrictions.
They are literally everywhere - millions upon millions of invasive gold clams within touching distance from the banks of the Waikato River - read about it here.
“Watercraft access will be preserved for four days a week, Friday to Monday daily 6am to 8pm, until April 29 2024, subject to meeting Check-Clean-Dry requirements.