NEW YORK, Nov. 9 (Reuters) - Royal Caribbean Cruises RCL.N said that lower-than-usual prices for holiday cruises and Florida's sluggish economy would pinch fourth-quarter revenue and it forecast a loss for the period.

The world's second-largest cruise operator projected a loss of 5 cents per share for the fourth quarter.

The company said that bookings for holiday cruises were not commanding their usual premium. Eleven percent unemployment and a weak real estate market in Florida would also dent results.

''The fourth quarter has historically always been the most price-sensitive quarter,'' said Chief Executive Richard Fain in a Reuters interview. ''If you're at the margin, relatively small changes in a steeper curve end up having a bigger impact.''

Royal Caribbean's earnings fell 44 percent for the third quarter, but surpassed analysts' expectations as close-in bookings showed strength. Cruise bookings since mid-September were up 40 percent compared with the same period last year.

''Investors remained concerned that softer demand/pricing dynamics in 4Q09 could spill over into 2010,'' said Stifel Nicolaus analyst Steve Wieczynski in a note.

Fain said he understood worries about future results, but said the company stood by its comments about next year.

''I'm well aware that there are many people that are more pessimistic about the future,'' Fain said. ''We're not really so much predicting the future as we are extrapolating booking trends.''

He added: ''Based on the bookings we're seeing, even without a big upturn in the economy, we felt pretty good about making a forecast of positive yield improvement.''