Repair work on the huge hole under Auckland's Ferry Building is expected to start on Monday.
Auckland Transport has warned of changes to ferry arrival and departure points to allow the erosion at the base of the building's seawall to be fixed.
Pier 1A will be closed completely for the repairs, which are expected to take between six and 10 weeks.
The hole was first discovered in October last year, but had doubled in size by August to 16m long and 4m high. Experts recommended it be looked at immediately.
Bayswater, Birkenhead and some Half Moon Bay ferries would now depart from Pier 1C, while some Half Moon Bay afternoon services would move to Pier 2B.
There would be no changes to Devonport, Stanley Bay or Waiheke services, AT's ferry services manager Gareth Willis said.
"We are making sure everyone knows about the changes, we're telling people in the ferry terminal, on board the vessels and online about what's happening. Once people become used to the new arrangements, we are aiming for business as usual.
"We will continue to work closely with all operators and the contractor, STF to ensure we minimise disruption to the public while the works are taking place."
Contractors STF Limited were experienced marine repairers, AT said.
Updates would be available on the AT website.
Departure points from Monday October 9:
• Pier 1B - Devonport and Stanley Bay (no change)
• Pier 1C - Bayswater, Birkenhead and Half Moon Bay
• Piers 2B and 2C - Waiheke (no change)
• Pier 2B - Half Moon Bay services departing at 4.15pm, 5.15pm and 5.45pm (all others depart at Pier 1C).