They say that a rising tide lifts all boats. I'm not entirely sure who "they" are, but the advice is usually sound, nonetheless, particularly when it applies to cruise ships. Cruising continues to gain in popularity, and despite a few high-profile setbacks, vacationers are embarking for exotic ports of call in record numbers, billowing the financial sails at Carnival (NYSE:CCL). After reporting a favorable first-quarter tailwind three months ago, the world's largest cruise operator is still making steady progress on its fiscal 2005 voyage.

This morning, the company posted net income of $409 million, a 23% increase over the $332 million earned a year ago, on revenues that climbed nearly 12% to $2.52 billion. Previously canceled cruises clipped $0.03 off the bottom-line results, but earnings still came in at $0.49, easily topping expectations.

Rising fuel costs remain a concern, as a 35% spike in prices drove costs per available lower berth day -- a core measure of expenses in the industry -- up by 7.3%. However, revenues per available berth day more than kept pace, rising a brisk 8.4% during the quarter. This key metric (also referred to as net revenue yield), which reflects both occupancy and ticket prices, has now increased at a 7%-plus rate for five consecutive quarters.

Carnival has shown a remarkable ability to continually soak up more capacity. Following a 17% increase in 2004, capacity now stands 8.5% above levels from a year ago. Nevertheless, occupancy rates for the second half of the year are tracking above where they were at this point last year, and average ticket prices have been on the rise as well. Rival Royal Caribbean (NYSE:RCL) hasn't had much trouble filling the extra cabin space, either. Earlier this year, it announced an occupancy rate of 105.7% (some berths held more than the standard two passengers), despite having increased capacity by double digits.

With both companies reporting strong bookings for the remainder of the year, Steiner Leisure (NASDAQ:STNR) should find plenty of people lining up to be pampered. The onboard spa-treatment specialist, which provides guest services for Carnival, Royal Caribbean, and Disney (NYSE:DIS), has made a habit out of beating Wall Street expectations lately.

With a worldwide 78-ship fleet that makes up 12 different cruise lines, Carnival has an industry-leading 134,000 berths available. The company is also expecting to launch a dozen new ships over the next several years. Assuming it can keep finding the demand to meet that capacity -- something that hasn't been a problem so far -- future growth rates should remain attractive. Full-year earnings guidance has recently been lifted, and management is now targeting a solid 21% improvement over last year's bottom-line results.

For those who don't mind lugging around debt of more than $7 billion, a fairly heavy anchor for a ship of any size, Carnival may provide its shareholders an enjoyable ride.

Steiner Leisure is a Motley Fool Rule Breakers pick; climb aboard today by taking a free trial offer.

Fool Contributor Nathan Slaughter owns none of the companies mentioned.