There are a lot of reasons for investors to be worried, but the stock market doesn't seem to be paying much attention to them. Even with 1.87 million new claims for unemployment benefits once again topping what economists had expected to see, market participants remain steadfastly optimistic that the reopening of the economy will spur a recovery that will justify the indexes' recent moves higher. Just after 11 a.m. EDT, the Dow Jones Industrial Average (DJINDICES:^DJI) was up 86 points to 26,356. The S&P 500 (SNPINDEX:^SPX) rose 2 points to 3,125, and the Nasdaq Composite (NASDAQINDEX:^COMP) picked up 7 points to 9,690.

Cruise ship operators remain among the industries most affected by the coronavirus pandemic, and they've experienced some of the largest rebounds over the past couple of months. Yet even though the cruise line industry has seen some positive signs, it's also had to deal with challenges that could last a lot longer than some investors realize.

Solid gains for cruise ship stocks

Stocks in the sector were higher, with Norwegian Cruise Line Holdings (NASDAQ:NCLH) leading the way with a 7% rise. Carnival (NYSE:CCL) followed suit with a 5% gain, and Royal Caribbean Cruises (NYSE:RCL) managed to see its shares inch up 2%.

Two deck chairs on a ship near a railing, with ship wake and a sunset visible.

Image source: Getty Images.

The easiest explanation for the move higher is that the cruise ship industry stands to gain the most from a return to more normal conditions. As more businesses reopen, more people anticipate everything going back to the way things were before the pandemic hit. That includes being able to take cruise vacations the same way people did before.

Indeed, investors have been extremely supportive of cruise ship companies. Norwegian, Carnival, and Royal Caribbean have all turned to the capital markets for assistance in making it through their periods of suspended operations, and the offerings of stock and bonds have generally been well subscribed. Royal Caribbean said today it would issue three-year traditional and convertible notes, with the expectation of raising as much as $2 billion.

Will cruises ever go back to normal?

Some people aren't sold on the bullish case for cruise companies, however. Analysts at Morgan Stanley believe that the stocks have climbed much too quickly, especially given the specific challenges that the cruise industry faces. Even though air travel is getting more popular and hotels are seeing occupancy rates rise, Morgan Stanley believes that cruise lines could well be the last niche of the travel industry to reopen doors and resume operations.

That's largely because the cruise industry has a poor reputation for health matters, and governments are paying special attention to their operations. Canada, for instance, has banned cruises in its territorial waters through the end of October. Just today, Carnival said it would extend suspension dates on voyages from Australia and Taiwan, as well as Canada.

Even so, cruise operators are hopeful that the U.S. will be more lenient. Even with an ongoing no-sail order from the Centers for Disease Control and Prevention, cruise ship companies hope to sail on a limited basis by the middle of summer.

Optimism about the broader economic reopening is lifting the entire market, including cruise stocks. However, investors in the cruise operators should be on guard for signs that those companies won't fully participate in a recovery -- and need to be aware of the possibility that cruises might never look the same as they did before the outbreak struck.