THE world's biggest cruise ship has left Southampton for the first time.

The Harmony of the Seas departed the city this afternoon on a two-day preview voyage around the English Channel.

Towering over her surroundings, the enormous vessel was watched from the shoreline by dozens of people as she left the port and made her way down Southampton Water and into the Solent.

After the cruise, she will then set off on its maiden voyage to Rotterdam, before another voyage to Cherbourg.

The 227,000 ton giant is the largest cruise liner in the world, and is 1,188 feet long and 215.5 feet wide.

The Royal Caribbean liner will carry 6,780 guests and 2,102 crewmembers on voyages around the Mediterranean and Caribbean, and will be based in Barcelona during the summer.

As well as 20 restaurants, 23 swimming pools and several bars, the ship also boasts robot bartenders, a central park and a theatre hosting performances of Grease, and cost $1billion to build.

The Harmony of the Seas will travel around the Isle of Wight on its Channel cruise, returning to Southampton at about 5.30am on Sunday.

Her departure came as Royal Caribbean announced a seven-year deal for the Port of Southampton.

The firm will spend £5.5m to improve its terminal and allow larger ships to dock, with the company saying it could be worth as much as £200m to Southampton's economy.