A Royal Caribbean cruise ship has been forced to dock in Sydney after severe storms smashed the city and more than 180 passengers were struck by gastro.

The Explorer of the Seas docked at around 6am on Wednesday after it was hit with a double emergency when passengers became sick and bad weather rocked the ship.

The storm was so severe that huge waves in Sydney Harbour caused the vessel to tilt at 11 degrees, causing many of the passengers to panic, reported nine news.

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182 passengers on board the Royal Caribbean cruise ship Explorer of the Seas were struck with gastro

'I felt it tip, and then you're just waiting for it to straighten back up and it didn't and it tilted a bit more,'

'I thought, "it's gonna straighten [sic]"… and then I panicked,' a woman on board told 9NEWS.

The captain told passengers the ship tilted at 11 degrees as it was hit by 40 knot winds, however passengers claim to have felt the ship tip at 45 degrees.

A build up of water rushing of the top deck was recorded by passengers as well as the alcohol bar looking chaotic with broken bottles laying across the floor.

NSW Ambulance paramedics were waiting for the vessel to arrive in order to examine the passengers on board.

From the 4,700 passengers aboard the ship no patients needed to be taken to hospital.

Videos from on boards the ship shows water flowing of the top deck as a freak wave hits the cruise ship

The bar on board the cruise ship also looked chaotic as bottled lay broken across the floor

The ship was travelling from New Zealand on a 14 day cruise and was arriving in Sydney to take on more passengers before continuing on Wednesday afternoon.

The outbreak is believed to have started on December 4 and extra cleaning is expected to be undertaken today in a bid to control the outbreak.

Royal Caribbean told Daily Mail Australia in a statement that the illness was short lived and all new guests will need to advise staff of any previous gastrointestinal symptoms.

'Those affected by the short-lived illness have responded well to over-the-counter medication administered on board the ship.

'At Royal Caribbean International we have high health standards for all our guests and crew.

'All new guests embarking will receive a letter at boarding that asks them to advise if they have experienced any gastrointestinal symptoms within the last three days,' said the statement.

The outbreak is believed to have started on December 4 and extra cleaning is expected to be undertaken today in a bid to control the outbreak