An Air New Zealand spokesman said about 60 passengers were affected when heavy fog disrupted two early ATR services.
Flight NZ5741, due to land in Dunedin at 7.45am, instead returned to Christchurch, and Flight NZ5742, due to leave for Christchurch at 8.15am, was cancelled.
The affected passengers took alternative flights.
The bulk carrier Yangtze Spirit and the fishing vessel Fortunui were due to arrive at their harbour berths at 6.30am and 7am respectively, but thick fog persisted until about 1.30pm.
The vessels were rescheduled to reach their berths late yesterday afternoon.