Royal Caribbean has just raised a fee that many cruisers find quite surprising

Bad news for Royal Caribbean enthusiasts: You're going to face even higher fees to cruise with the line.

This week, the world's largest cruise company started informing customers that the automatic service charge added to passenger bills will soon increase to as much as $21 per person, per day.

In emails sent to passengers with upcoming bookings, the cruise line announced that the daily gratuity charge, as they refer to it, will rise to $18.50 per person, per day on November 1 for most cabins, while those in suites will pay $21 per person, per day.

These new rates represent an increase of approximately 3% over Royal Caribbean's existing service charges of $18 for standard cabins and $20.50 for suites.

Although the gratuity charge increase is relatively small in percentage terms, it marks the second rise within a year, leading to a total increase of nearly 14%. This time last year, Royal Caribbean charged only $16 for service fees for most cabins.

With this increase, a family of four in a standard cabin will incur over $500 in automatic gratuities on a seven-night cruise — one of the highest charges in the industry.

Compared to other major lines, Carnival Cruise Line, MSC Cruises, Princess Cruises, and Holland America charge between $10 and $16 per person, per day in service fees for most cabins, while Celebrity Cruises imposes an $18 fee per person, per day in gratuities.

Royal Caribbean's gratuity charge has surged by an impressive 54% since early 2015, when it was only $12. The line has raised rates five times during that period.

The 54% rise in Royal Caribbean's gratuity fee since early 2015 exceeds the U.S. inflation rate by approximately 19 percentage points over the same timeframe.

According to the U.S. Department of Labor, inflation in the U.S. has accumulated to about 35% since early 2015, as indicated by the Consumer Price Index for All Urban Consumers.

Most major cruise lines, including Royal Caribbean, Carnival, and MSC Cruises, automatically apply some type of service or gratuity fee to passenger bills. Passengers usually have the option to prepay these fees when booking or have them added to their onboard expenses, settled at the end of the cruise.

However, the overall number of lines charging a service fee has been decreasing over the years. Many smaller and upscale cruise lines now include these charges in their base fares.

Cruise lines that now incorporate gratuities into their fares include Azamara, Ponant, Explora Journeys, Crystal, Regent Seven Seas Cruises, Scenic Luxury Cruises & Tours, Seabourn, SeaDream Yacht Club, Silversea Cruises, and Virgin Voyages.

For those lines that do impose them, service and gratuity fees are marketed as a convenient substitute for cash tipping on ships — a practice that was once quite common.

Cruise lines that implement such charges generally raise their rates every year or two.

Royal Caribbean informed customers with existing cruise bookings that they could secure the current, lower gratuity rates by prepaying before November 1.

It's important to note that passengers dissatisfied with the service on Royal Caribbean ships can modify the daily gratuity amounts charged to their accounts while onboard by visiting the Guest Services desk, as per the line's policy.

Adjustments are only permitted when gratuities are billed to onboard accounts during sailings. Passengers who have prepaid their gratuities cannot change the amount paid while on the ship.