Shares of Carnival (NYSE:CCL) (NYSE:CUK) opened 6% higher today, after the leading cruise-line operator raised its outlook for all of 2009.

This is a welcome surprise. The way that fuel prices -- a key cost component in the industry -- have been inching higher in recent weeks, the logical wager would have been on seeing Carnival lower its profit targets.

Travelers are apparently warming up to hitting the high seas on Carnival's floating resorts. It started when the cruising giant was able to get away with better-than-expected last-minute pricing for its summer bookings during its latest quarter.

Things have only been getting better. Since June, booking volumes for sailings during the next four quarters are running 19% ahead of where they were a year ago.

Still, despite the recent uptick in the number of bookings, Carnival's net revenue yields -- an industry metric that divides revenue by available lower berths per day -- are still lower than they were a year ago.

Add it all up, and Carnival expects to earn between $2.16 and $2.20 a share this fiscal year, well ahead of its earlier $2.00-to-$2.10 projection.

The good and the bad in Carnival's report can be applied to rivals Royal Caribbean (NYSE:RCL), NCL, and Disney (NYSE:DIS). If passengers are guarding their pocketbooks a little closer, that will also affect Steiner Leisure (NASDAQ:STNR), the company that manages the spas on most of the industry's ships.

If cruisers choose to steer clear of the onboard casinos or avoid the Caribbean gambling hot spots, that also affects gaming-equipment companies including IGT (NYSE:IGT) and Shuffle Master (NASDAQ:SHFL).

Improvement at Carnival -- even if it's simply relative to its prior expectations and not on an absolute basis -- ripples through many publicly traded waters.

Call off the Coast Guard, for now. The lifeboats can stay high and dry.  

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Longtime Fool contributor Rick Munarriz considers discounted cruise trips one of the many perks of living in Miami. He owns shares in Disney and is also part of the Rule Breakers newsletter research team, seeking out tomorrow's ultimate growth stocks a day early. The Fool has a disclosure policy.