BAYONNE - A Royal Caribbean cruise ship, on which hundreds of passengers and crew members fell ill, arrived back Port Liberty in Bayonne Wednesday.

The Explorer of the Seas departed from Bayonne last week on a 10-day voyage, and was forced to return two days early, due to the illnesses.

The U.S. Centers for Disease Control and Prevention said its latest count puts the number of those sickened aboard the vessel at 630 passengers and 54 crew members.

"Everybody was getting sick," says passenger Maria Frank. "They had diarrhea. They were throwing up. It was just horrible."

Some passengers say those who got sick didn't take proper precautions, and spread the virus to others by not staying in their cabins.

Royal Caribbean says most guests who fell ill were up and about when the ship returned to Bayonne. It arrived just after 1:30 p.m.

At least one passenger was loaded into a waiting ambulance upon disembarking.

The CDC is recommending that passengers who still have symptoms should stay in nearby hotels or be seen at medical facilities.

Health investigators suspect a norovirus is to blame. If it is, the CDC says it would be one of the worst cruise ship norovirus outbreaks in 20 years.

The cruise line has offered passengers a 50 percent refund, half-price off their next cruise and reimbursed travel expenses as a result of the early return. Many passengers say they appreciate the gesture. "I think Royal Caribbean did an excellent job," says Henry Lempicky. "And I think the crew did an outstanding job with the extra cleaning."

Royal Caribbean says the ship will be thoroughly cleaned in Bayonne. A Florida-based firm is sanitizing the boat from top to bottom. "We'll be wiping all touch points to sanitize the cruise ship," says Rick O'Shea, of ByoPlanet, "They'll be using our electrostatic technology to go ahead and coat all surfaces."

O'Shea says it takes 8 to 12 hours to clean a ship of Explorer's size.

The ship is scheduled to set sail with a new group of passengers on Friday.