The 2,850-guest, 122,000-tonne Celebrity Equinox will spend the next two weeks in Southampton for her inaugural celebrations.
It is the only cruise ship to be launched in the UK this year as the global recession bites. Last year there were three launches.
The number of people taking cruises has also stalled after more than ten years of growth.
Figures from the Passenger Shipping Association showed that last year 1.5 million British holiday makers opted for a cruise, an increase of 11 per cent compared with 2007 but the figure is expected to remain the same for this year.
Celebrity Equinox is in the South Coast port ahead of its sister ship Celebrity Eclipse which is currently under construction and will be based in Southampton from next summer.
The company predicts its increased operations in the UK cruise market for 2009 and 2010 will generate more than £20.5 million in knock-on benefits for the local economy.
Spokesman for Royal Caribbean, who own the ship, Robin Shaw, said: "For the UK to be hosting the inaugural celebrations of Celebrity Equinox demonstrates the importance of the British and Irish markets.
"The reaction of UK consumers in terms of bookings is strong with sailings during all peak holiday periods sold out."
The company said the £700 million ship is aimed at experienced cruisers.
The real grass lawn on board is larger than eight tennis courts and can be used for boules, bocca, putting and outdoor concerts.
The German-built ship also has the usual attractions such as a casino, ten restaurants and pools.
Celebrity Equinox is also one of the first cruise ships to use renewable energy resources and the power generated by 61 on-board solar panels is enough to operate all the onboard lifts.
The first sailing with paying guests on board is sold out and departs from Southampton on July 31 for an eight-night Norwegian Fjords cruise.
The liner will officially named and christened in Southampton on July 29 by the founder of the breast cancer charity Walk the Walk, Nina Barough CBE.