The world's biggest passenger liner, the Queen Mary 2, could generate business worth £75m a year for Southampton, according to its owners.
The Queen Mary 2 arrived in Southampton in fog and rain
The £550m luxury ship, which will cater for 2,620 passengers each time it sails, will boost trade in the city more than any previous ship, they say.
Pamela Conover, the president of the Cunard Line said: "The benefits are significant.
"We estimate that the annual contribution the ship will bring will be at least £75m a year to the economy of Southampton and the area."
BBC South's transport correspondent, Paul Clifton, said: "That works out as three billion pounds to Southampton over the life of the ship.
"Everyone from taxi drivers to florists benefit."
President of Cunard Line, Pamela Conover
For the next fortnight, the 150,000-tonne ship will dominate the city's skyline after more than 100,000 people watched her negotiate the busy Southampton Water at about 1150 GMT on Boxing day.
Some 200 shipyard workers are adding the finishing touches to the super liner, which will be shown off to representatives from the world's travel trade over the next two weeks.
Queen Mary 2 (QM2), the first new transatlantic liner for a generation, will by named by the Queen on 8 January.
Her naming ceremony is expected to be low key, following last month's tragedy when 15 people died after a gangway collapsed while the liner was in dry dock at her shipyard in Saint Nazaire, France.
For her maiden voyage in January, the 1,132ft (345 metres) ship will take 2,620 passengers and 1,253 crew on a two-week cruise to Fort Lauderdale, Florida.