MIAMI (Bloomberg) -- "What do you need to fall in love again?'' a woman asks in the television commercial, as a scantily clad couple caress each other.

"Westerly winds. Blue, blue water. Mahi-mahi with wild rice. A really nice ship. It's different out here.'' "Here'' is on the high seas, where cruise ships are trolling for customers with seductive mood advertisements like the one by Norwegian Cruise Line.

They're also offering big bargains, as the cruise industry tries to lift itself out of the worst extended slump in at least 15 years.

Bookings in the $7 billion-a-year industry have slowed during the past year, and some major cruise lines are predicting weak sales into the fall. The number of passengers dropped 4.5 percent in the first three months of the year, accelerating a slight 1994 decline. In contrast, growth barrelled along at 9.3 percent annually during the previous 13 years.

Analysts cite a couple of factors: slack consumer demand in the economy, and public nervousness about outbreaks of illness aboard a few ships. In late July, about 220 passengers on Celebrity Cruises Inc.'s Horizon reported symptoms of salmonella poisoning, a year after an outbreak of Legionnaires' disease struck passengers on the same ship.

Cruise operators' profitability has been hurt as a consequence, with the exception of industry leader Carnival Corp., which has a strong marketing and moderate-price strategy. No. 2 operator Royal Caribbean Cruises Ltd.'s earnings have been dragging, and it is pushing an aggressive discount promotion to revive sales. "Cruise lines have had to work harder to fill beds,'' said James Godsman, president of Cruise Lines International Association. "Some are doing well, and others are finding it to be a challenging marketplace.'' And a big new competitor looms on the horizon -- Walt Disney Corp. The entertainment company, already a big presence in Florida with Disney World, plans to enter the cruise industry in 1998, and will feature 2,400-passenger "mega-ships.'' The four biggest lines -- Carnival, Royal Caribbean, Princess Cruises and Norwegian Cruise Line -- all said they are using price discounts to encourage early bookings and fill empty berths.

Royal Caribbean has taken perhaps the most aggressive tack. It reduced rates on many summer sailings by between $30 and $150 a cabin, and lowered advance-booking rates by $50 starting in September.

Of the 40 cruise operators in the US, the smaller ones have generally been hurt the most. But even some of the biggest lines have been thrown off course.

Royal Caribbean, the second largest cruise line, said that its bookings have been soft since December and will continue so through the third quarter. The company's price cuts will cost it a total of $12 million over the next couple of years.

The Miami-based company's earnings have been dragged down as a result.

Second-quarter earnings fell to 50 cents a share from 53 cents. For the first half of the year, the results dropped to $1.01 from $1.09.

Royal Caribbean's stock has fallen 25 percent since October, trading at 21 5/8 yesterday.