At least eight cruise ships carrying more than 20,000 vacationers have been forced to alter course this week to avoid Hurricane Michael.

Cruise giant Carnival's 2,124-passenger Carnival Miracle on Tuesday skipped a call at Cozumel, Mexico, as it steered clear of the storm. The ship departed Tampa on Sunday on a seven-day voyage to the Western Caribbean.

Also shifting course on Tuesday was Carnival's 2,040-passenger Carnival Paradise, which is on a five-day voyage out of Tampa. The ship is sailing a reverse itinerary that will see it arrive in Cozumel on Wednesday and Grand Cayman on Thursday.

The vessels joined four others at Carnival that had been forced to reroute earlier in the week due to Michael's approach. On Monday, the Miami-based, 2,980-passenger Carnival Glory skipped a call at Grand Cayman and remained at sea to avoid the storm while the Galveston, Texas-based, 2,754-passenger Carnival Freedom dropped a call at Mahogany Bay in Honduras.

The New Orleans-based, 2,754-passenger Carnival Triumph and Miami-based, 2,764-passenger Carnival Victory are sailing reverse itineraries.

The storm also has forced Norwegian Cruise Line to alter the itinerary of one of its biggest ships, the 4,248-passenger Norwegian Getaway, and at least one Royal Caribbean vessel has seen its itineraries slightly adjusted.

Norwegian's Miami-based Getaway called Tuesday at Falmouth, Jamaica, in lieu of Roatan, Honduras. On Wednesday, it substituted a call at Grand Cayman for Costa Maya, Mexico.

On Wednesday morning, Royal Caribbean chief meteorologist James Van Fleet said in a tweet that the line's 2,350-passenger, Tampa-based Majesty of the Seas would arrive back at its home port on Thursday several hours late due to the storm.

Van Fleet also said Royal Caribbean's 1,992-passenger Grandeur of the Seas might depart Baltimore two hours early on Thursday to steer clear of the storm.

The National Hurricane Center on Wednesday said the Category 4 storm is expected to move ashore over the Florida Panhandle on Wednesday afternoon, becoming the strongest hurricane in recorded history to hit the region.

As of 8 a.m. EDT Wednesday, Michael was about 90 miles south of Panama City, Florida, and moving north at 13 mph. The hurricane had maximum sustained winds of 145 mph.