Carnival Corp is getting some ships ready to start sailing again, while keeping others at anchor for even longer as part of a patchwork approach to returning nine brands to service.

The Arnold Donald-led owner of 90 ships plans to start untethering Costa Cruises' 11 ships from Italian ports and AIDA Cruises' 13 vessels from German terminals on 6 September.

The New York-listed company is making these moves after receiving proper authorisations from the government of Italy, the flag state for both brands' ships.

The first Costa Cruises ship to set sail will be the 2,260-berth Costa Deliziosa (built 2010) on 6 September, offering weekly cruises from Trieste to Greece.

The 4,947-berth Costa Diadema (built 2014) will follow on 19 September, operating seven-day cruises in the Western Mediterranean from Genoa to Italy and Malta.

"From the entry into force of the new decree by the Italian government, Costa Cruises is working with flag state authorities and the destinations to ensure a responsible, smooth and well-organised application of the new regulations and protocols," Costa Cruises said in a statement.

All other Costa Cruises ships will stay idle through September as the Italian brand, which expects to announce itineraries for the Costa Deliziosa and Costa Diadema in the coming days, works with local health authorities, harbour masters, ports and RINA.

"Costa is informing the impacted guests and travel agents," Carnival said.

"They will be guaranteed a reprotection in accordance with the applicable legislation."

Costa Cruises said it has developed a Covid-19 safety protocol for its fleet that includes new operating procedures.

This protocol has arrived, however, as the brand faces a lawsuit from more than French passengers who came down with Covid-19 symptoms while aboard the Costa Magica in March.

AIDA Cruises will resume sailing along with Costa Cruises

AIDA Cruises is planning to resume its cruise operations with the first trips from Kiel starting on 6 September.

The first cruises with the 3,300-berth AIDAperla (built 2017) to the Norwegian fjords start from Hamburg on 12, 19 and 26 September, the brand said.

"In the coming days, AIDA Cruises will review the specific details of this decision and will work closely with all responsible authorities of the flag state Italy and the classification society in order to carefully implement the new protocols and regulations in the sense of a responsible restart on board the AIDA ships," the brand said.

"As the current development shows, unfortunately not in all European travel destinations the prerequisites for safe travel are given yet."

Like Costa Cruises, AIDA Cruises plans to extend the pause for the rest of its fleet through 30 September.

"To AIDA Cruises it is important to provide all guests with this important information regarding their vacation," it said in a statement.

"The company very much regrets that the other voyages cannot take place as planned. All guests whose cruise cannot be carried out will be informed immediately."

P&O Cruises and Holland America Line staying put

Meanwhile, P&O Cruises plans to keep its ships motionless for longer than originally planned.

The brand, which caters to passengers from the UK and Australia, has extended its fleet pause to 12 November and cancelled two January 2021 itineraries per Foreign & Commonwealth guidance.

"Given long-term planning, combined with the complexity and length of these long-haul itineraries and evolving border restrictions, we need to ensure that we adhere to the guidance as it stands," chief executive Paul Ludlow said in a statement.

“We continue to work in partnership with public health agencies at the highest level as well as Department for Transport; EU Healthy Gateways and Cruise Lines International Association."

Carnival has also extended its fleet suspension through 15 December.

The pause extension affects the Caribbean, Mexico, Panama Canal, Pacific Coastal, South America, Antarctica, Hawaii, South Pacific, Australia and Asia itineraries.