What happened

By now you've heard the news: Another bank is in trouble, with shares of Credit Suisse tumbling 20% (through 11:45 a.m. ET this morning) on accounting worries, and this on top of the failures of a pair of American banks over the weekend.    

Markets are all shook up, with the S&P 500 falling 1.4% today and the Nasdaq down almost 1%. Cruise stocks are getting hit particularly hard, with Norwegian Cruise Line Holdings (NCLH 0.35%) stock falling 3.4%, Carnival Corporation (CCL 1.66%) (CUK 1.49%) down 4.3%, and Royal Caribbean (RCL 1.58%) falling 4.6%. But what does trouble in the banking sector have to do with falling cruise stock prices, exactly?

So what

At its core, this is a macroeconomic story. The more banks run into trouble, you see, the greater the "risk" that banks will start acting more conservatively. And while ordinarily you'd think that would be a good thing (aren't banks supposed to be conservative, verging on stodgy?), the downside of cautious bankers is that they might lend less -- and charge more for their loans.

This, CNBC worried aloud today, raises the potential for "a credit crunch happening in the United States."  

Now what

Well and good. So what does "a credit crunch" have to do with cruise line stocks? Why should "a credit crunch" make cruise investors nervous?

Basically, it's because cruise companies are carrying a whole lot of debt right now, which they took on to keep their operations alive through the pandemic, and which they haven't yet had a chance to pay off. At last report, Carnival is the most heavily indebted cruiser, with $31.9 billion more debt than cash on its balance sheet -- and no positive free cash flow with which to pay that debt down.

Royal Caribbean is a bit better off, with "only" $22 billion in net debt. Norwegian Cruise carries the least debt, a relatively svelte $13.2 billion. (Then again, Norwegian is only one-third the size of Royal Caribbean by market capitalization, so its debt is actually a relatively bigger burden).

Any way you slice it, though, debt is already a big problem at these companies, costing Carnival $1.6 billion in interest expense last year, subtracting $1.4 billion from Royal Caribbean's profits, and siphoning $608 million away from Norwegian Cruise's shareholders as well (according to data from S&P Global Market Intelligence). If banks respond to the current banking crisis by imposing tougher terms on their lending -- for example, by charging higher interest rates -- you can expect these interest costs to swell and make it even harder for the cruise companies to earn a profit.

How bad will things get for the cruisers? To find out, tune in before market open on March 27, when Carnival Corporation will report its Q1 2023 earnings.

Analysts are forecasting a $0.60-per-share loss.