MARK WALLHEISER / EPA A young passenger waits to board a bus after disembarking from the crippled Carnival Triumph cruse ship after it was towed to port in Mobile, Alabama on Feb.14 2013.

So you’ve survived for five days stranded at sea aboard the Carnival Triumph. The ship had no working toilets, sewage dripped from walls, and the whole place smelled “like a hot port-o-potty.” Here’s $500 for your troubles.

Last week, after the Triumph was finally tugged into Alabama and passengers kissed solid ground in relief, Carnival announced that all passengers on the ship—which was hit with a fire in an engine room and left without power in the Gulf of Mexico—would receive some compensation. The offer included a full refund for the cruise and travel expenses, reimbursement for nearly everything they spent on board the ship, a credit good toward a future cruise, plus a check for $500.

To some, the offer didn’t exactly seem generous. “I would have expected more really,” said travel expert George Hobica, who runs the deal-finding site AirfareWatchdog.com. “I think giving them their money back and $500 is pretty cheap.”

Carolyn Spencer Brown, editor of CruiseCritic.com, had basically the same reaction. “What these people went through was worth more than $500,” she said. “It’s a little bit insulting. It’s almost as if Carnival would have been better off offering nothing than to go so low.”

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So where did Carnival come up with the $500 figure to begin with? The cruise line didn’t explain. In situations involving refunds and compensation for travelers, there usually isn’t much explanation other than that the policies and dollar figures somehow seem about right. “It’s all about PR,” said Brown. “This was probably determined by the marketing department more than anybody.”

Calamities like the Triumph can obviously be bad for the cruise line at the center of the storm. They can also damage the cruise industry as a whole. In the aftermath of the sinking of the Costa Concordia—which just “celebrated” its one-year anniversary last month—cruise prices decreased by 12%.

To minimize the public-relations damage, to salvage some sort of goodwill with affected customers, and also to cut off lawsuits before they are filed, travel operators are known to offer compensation during the worst situations. Concordia passengers were offered around $15,000, on top of a refund and travel expenses.

At the time of the offer, a lawyer representing the cruise line told the Associated Press that there were big upsides for passengers who accepted the payment: “The big advantage that they have is an immediate response, no legal expenses, and they can put this whole thing behind them.”

Funny: The cruise lines involved in these disasters also want to avoid legal expenses and put the whole thing behind them.

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But about the payouts: Where do the figures come from? When vacations are ruined, compensation paid to travelers can run the gamut, from bupkis to tens of thousands of dollars. Are the amounts purely at the discretion of some travel company executives?

Well, under certain circumstances, airlines and cruise lines are obligated by law to compensate customers whose trips have been adversely affected. For instance, Department of Transportation regulations require airlines flying within the U.S. to compensate passengers who are denied boarding because a flight is oversold. If the airline gets such a passenger on another flight that lands within one to four hours of the originally scheduled arrival time, the carrier pays the delayed traveler 200% of the original one-way fare, up to $650. If the traveler is delayed by four hours or more, the compensation goes up to 400%, and a maximum of $1,300. On the other hand, if the airline gets such a passenger onto another flight that lands within one hour of the original arrival time, no compensation is required at all.

The contract cruise passengers agree to stipulates specific instances when compensation will be provided by the cruise line. The Princess Cruise Line Passage Contract, for instance, lists scenarios such as this:

If Carrier cancels the Cruise before it has started, it shall refund the Cruise Fare (less any air or accommodation charges incurred).

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Well, you’d hope that if the cruise is cancelled, refunds would be in order. For the most part, however, the contracts travelers unknowingly sign off on are loaded with language that absolves cruise lines and carriers of responsibility for all sorts of delays, changes, and general disappointments. Here’s one passage from the contract for Princess Cruises (the “Carrier” mentioned in legalese below):

You shall have no claim against Carrier, and Carrier shall not be liable for damages or a refund of the Cruise fare, any portion thereof, or other refund, payment, compensation or credit of any kind; nor for hotel or meal charges, travel expenses or other loss, delay, inconvenience, disappointment or expense whatsoever, which shall be the Passenger’s responsibility, whenever the cancellation or change was beyond Carrier’s exclusive control.

For flights within the U.S., the DOT requires airlines to compensate passengers whose checked baggage is lost, delayed, damaged, or stolen, to the tune of up to $3,300. Yet most passengers never get anywhere near that amount, partially because airlines state that they’re not liable for all sorts of things when they’re placed in checked luggage. The Hawaiian Airlines site stipulates that the carrier is not responsible for an enormously long list of goods “including but not limited to items” such as:

Sculptures; paintings or pictures, framed or unframed; and models. Sconces; decorative screens; items of decorator stones; marble, onyx and alabaster; vases; figurines; trophies; souvenirs … sewing machines, watches, clocks, sensitive calibrated tools and instruments, televisions, radios … Glassware, crystal, mirrors, bottles and any liquids contained therein (excluding reasonable quantities or toiletries), prescription or non-prescription sunglasses, eyeglasses and contact lenses … Business/personal documents, negotiable papers, securities, manuscripts, publications (including manuals and textbooks), mechanical drawings, blueprints, maps … Cameras, camera lenses, film … Backpacks, sleeping bags, and knapsacks (and contents thereof) … Microscopes, oscilloscopes, telescopes, barometers, binoculars, meters, counters, Polygraphs electrographs, medical equipment

And on and on. The point is this: For the most part, airlines and cruises are not obligated by law to compensate customers when things go badly on a trip.

If a domestic flight is delayed or cancelled, the airline isn’t required to put passengers up in hotels or provide food or other amenities. You’ve probably heard about cruise passengers coming down with Norovirus on ships, but, as a CruiseCritic post stated plainly, “Cruise lines are not required to compensate guests who fall ill on a voyage.”

Nonetheless, airlines often do offer passengers hotels, or at least bottled water and snacks, when flights are delayed or cancelled. Cruise lines often do offer customers refunds, vouchers or discounts on future cruises, airline and hotel reimbursements, or other forms of compensation when a cruise itinerary is changed or half the ship’s passengers are hit with a virus.

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Why do they do so, then, when they’re not required? As mentioned above, it’s in their business interests to do so. “Carnival isn’t required to do anything,” said consumer travel advocate Christopher Elliott. “It appears to be acting only because of the intense media scrutiny.” Cruise lines and airlines take action because they want to minimize the damage and avoid lawsuits, with the idea that hopefully not too far in the future the traveling public will forget the whole thing happened.

Considering the horrendous conditions aboard the Triumph—rotting food, backed-up toilets, awful smells all around—this is one cruise industry black eye that’s likely to be remembered for a while. By most accounts, the staff aboard the Triumph maintained their professionalism throughout the ordeal and tried to help passengers as best they could. “The crew was always smiling,” one passenger said, according to USA Today. “They need a huge raise.”

Unfortunately for Carnival, and the cruise industry as a whole, this same passenger also had this to say after finally getting off the ship: “This is my first and last cruise.”

As for travelers who do keep on taking cruises, what happens if and when something like this happens again? Every situation is different. There’s no requirement for cruise lines to offer special compensation, and there’s no telling what each cruise line would do in any particular scenario. “No precedent has been set,” said CruiseCritic’s Brown. “The next time a cruise has a problem, passengers should not be expecting to get $500.”