The world's largest cruise line just canceled a boatload of additional sailings

Royal Caribbean has joined the growing list of cruise lines abandoning the idea of a return to service in the summer.

Citing the coronavirus pandemic, the world's largest cruise line by passenger capacity on Tuesday said it had canceled every sailing worldwide through Sept. 15.

Royal Caribbean's sister brand, Azamara, on Tuesday also canceled all sailings through Sept. 15, while sister brand Celebrity Cruises said it's canceled most voyages through Sept. 15.

Until Tuesday, the lines had been telling customers they would resume departures on Aug. 1.

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The cancellations come just four days after the main trade group for the cruise industry, the Cruise Lines International Association (CLIA), announced its members operating oceangoing ships would extend their suspension of cruises in U.S. waters until Sept. 15.

The CLIA announcement made it inevitable that Royal Caribbean and its sister brands would cancel sailings out of U.S. ports such as PortMiami through Sept. 15. But the three lines went further by cancelling August and September sailings around the globe.

Royal Caribbean is joining a lengthy list of cruise lines canceling sailings into September or beyond. Just Monday, Carnival Cruise Line said its ships wouldn't sail again until at least the first week of October. Norwegian Cruise Line and its sister brands, Regent Seven Seas Cruises and Oceania Cruises, also have canceled nearly all sailings into early October.

Cunard, Silversea, Seabourn, Holland America, Princess Cruises and Windstar Cruises also already have announced they won't resume sailings until the fall at the earliest.

Related: Why you shouldn't take a voucher for a canceled cruise

In addition to canceling all sailings worldwide through Sept. 15, Royal Caribbean has canceled Canada and Bermuda sailings through Oct. 31.

Most major ocean cruise lines that market to North Americans now have canceled every sailing through mid-September. But a few smaller ocean lines and river lines in various parts of the world are bucking the trend and gearing up for a restart of at least some operations.

A few small cruise vessels in Europe -- mostly river ships -- already have begun to restart sailings on a localized basis with trips aimed at the local market. The first was German line Nicko Cruises, which resumed river cruises in Germany with a single ship earlier this month. The trips are aimed at local Germans who can reach the ship by car or train.

Last week, Norwegian cruise and ferry company Hurtigruten restarted its famed ferry service along the coast of Norway, which often draws traditional cruisers as well as locals traveling between Norwegian towns. The company also plans to start up cruises from Germany for the local German market in the coming days.

Some small-ship cruising also is about to start up in French Polynesia.

Related: How I’m booking Tahiti (again) on points and miles

There's a growing consensus in the cruise industry that river ships and small vessels that sail coastal routings will be able to resume semiregular operations this year far earlier than the bigger ships that offer long-distance ocean trips.

In part, this is because small vessels offer a sort of small-group travel that is easier to manage in an era of social distancing than the mass tourism of big ships. The typical river ship in Europe, for instance, has fewer than 100 cabins. It essentially operates as a small boutique hotel — albeit one that happens to move from town to town. Touring always is in small groups or on an individual basis. Onboard spaces rarely are crowded.

Royal Caribbean, Celebrity and Azamara are offering passengers on the newly canceled departures a choice of a full refund or a credit in the amount of 125% of the amount paid.

Additional resources for cruisers during the coronavirus outbreak:

• When will cruising resume? A line-by-line guide
• Why you shouldn't expect bargain-basement cruise deals anytime soon
• How to cancel or postpone a cruise due to coronavirus
• Expecting a refund for a canceled cruise? Here's how long it will take
• Some of the year's hottest new ships could be delayed
• Stream these 13 movies, television shows to get your cruise ship fix