Cairns is accelerating maintenance dredging at its port after shallow water in Trinity Inlet forced cruise ships scheduled to visit the city to change their itineraries.

The problem has been caused by higher-than-usual siltation in parts of the shipping channel. Channel depths have fallen below the level required for some larger vessels to safely reach the Cairns cruise terminal, creating operational difficulties during the region’s cruise season.

One of the affected vessels was the Carnival Encounter, which carried almost 3,000 passengers and about 1,100 crew members. Instead of travelling north to Cairns, the ship docked in Townsville as part of its Great Barrier Reef itinerary.

A second Carnival vessel that had been scheduled to visit Cairns was also redirected, with the ship sent to Yorkeys Knob instead. The diversions mean thousands of cruise passengers who would normally have visited Cairns businesses, restaurants and tourism attractions were unable to spend time in the city during their scheduled calls.

Ports North has brought forward its maintenance dredging campaign to address the problem. Dredging operations are scheduled to begin on Friday, 18 September, and continue through early November under the existing environmental and marine permits.

The objective is to restore the shipping channel to its designed depth of 9 metres and maintain safe access for deep-draft vessels. Ports North has previously carried out regular maintenance dredging at the Port of Cairns to manage sediment accumulation and maintain suitable channel depths.

The organisation said unusually high siltation has also affected other Queensland ports, creating additional pressure on the availability of specialist dredging services.

The current disruption is particularly important for Cairns because cruise tourism contributes to the local economy. Cruise passengers can spend money on restaurants, retail businesses, tours, transport and other visitor services while ships are in port.

The diversion of the Carnival Encounter to Townsville demonstrates the economic impact that port-access problems can have on the region. Townsville was able to accommodate the vessel after completing a major channel-widening project that allows larger ships to enter its port.

Cairns authorities are now working to restore reliable access for cruise vessels as quickly as possible. The dredging operation will be conducted under the relevant environmental approvals, with the work subject to requirements designed to manage impacts within the Great Barrier Reef World Heritage Area.

The Queensland Government also issued a notice on 18 September confirming dredging operations in the Port of Cairns harbour and channel.

Once the maintenance work is completed, the aim is to return the channel to the required depth and reduce the likelihood of further cruise-ship diversions caused by sediment accumulation.

The issue remains important for Cairns tourism and local businesses as the city prepares for further cruise visits. Restoring dependable access for larger vessels will be a key part of maintaining the region’s position as a major Great Barrier Reef cruise destination.