In recent weeks, mammoth ocean liners have been moving in and out of San Diego’s downtown harbor, a welcome sign, in normal times, of a thriving cruise industry pumping tens of millions of dollars into the local economy.

But these are not ordinary times.

Far from signaling prosperity, the three Celebrity and Disney ships that are intermittently parked alongside San Diego’s waterfront are grim reminders of a global industry abruptly idled by the coronavirus, sickening people on land — and at sea. Instead of readying the ships docked here for future voyages to the Mexican Riviera and Panama Canal, the cruise lines are grappling with how to return hundreds of crew members still on board to their home countries in the Philippines and India. A few of the crew remain infected with the COVID-19 illness.

Where the Port of San Diego had forecast about 104 cruise calls accounting for 338,000 passengers through the end of its current cruise season this month, those numbers have now plunged by 30 percent since cruising was closed for business March 14 by the Centers for Disease Control and Prevention. The economic hit is estimated to be more than $50 million.

While the CDC’s extended “no sail order” isn’t due to expire until the end of July — well ahead of the scheduled fall start of San Diego’s new cruise season — no one really knows for sure when cruising, in whatever revamped form it takes, will resume. Major cruise lines last week began canceling many summer and fall sailings but not in San Diego.

Long before the coronavirus crash, port officials here had been anticipating a robust 135 cruise calls, accounting for close to half a million passengers, for the 2020-21 cruise season.