The cruise shore excursion, the day trip during the small amount of time passengers have in port, is among the most significant elements of a cruise vacation.
Whether it be a snorkeling trip to a coral reef, a guided tour of 2,000-year-old ruins or an exhilarating helicopter ride to a glacier, the best cruises include some exciting jaunts away from the ship, even as the vessels themselves increasingly take on the role of destinations.
But before the coaches, catamarans and all-terrain vehicles shuttle passengers from the piers, the politics that determined how those people ended up on the excursion they did is part of an often-contentious undercurrent in the relationship between the travel agent and the cruise line.
In simple terms, the agents want commissions for selling cruise ship shore excursions, while almost no cruise line will pay them.
This disagreement mattered less 10 years ago, travel agents say, because the commissions they made selling cruises alone were much higher.
But in recent years, with the rise of noncommissionable fees and with cruise fares at record lows, the loss of items that agents formerly made commissions on, such as airfare and hotels, and those they feel they should get commissions for, such as shore excursions, seem like more of a loss.
"Any incremental commission helps," said Steve Gelfuso, president of Rhode Island-based CruiseBrothers.com. "It used to be different, when the average cruise commission was $500 to $600. Now the average is so low."
There are exceptions.
MSC Cruises pays agents a 10% commission on shore excursions that are booked prior to departure. Regent Seven Seas includes many shore excursions in what it calls its "ultra-inclusive" pricing, meaning agents receive commissions for the additional cost of the tours in the fare.
But the largest cruise lines, and the ones most commonly booked by U.S. travel agents, do not pay commissions.
As a result, travel agents more than ever are turning to a growing number of third-party providers such as ShoreTrips, MyExcursions.com, PortPromotions.com and Shore Excursions Group.
Cruise lines, feeling threatened not only by the rise of independent tour companies but also by the ease with which their passengers can find them online, are fighting to retain this lucrative element of the cruise experience.
"The cruise lines used to have much more of a monopoly on shore excursions, because guests had access only to tours they found onboard," said a former executive with Norwegian Cruise Line. "With the Internet, guests research the ships and destinations thoroughly before leaving. They are finding independent tour companies and seeing the same tour for much less than what the ship charges."
Several agents agreed.
"Shore excursions are becoming a big point of contention," said Howard Moses, president of the Cruise Authority in Atlanta. "With the availability of private tours available throughout the Internet, and what are some very high pricing, too high in our mind, being charged by the lines, many people are booking their own tours either direct or via their travel agent."
Many cruise lines admit that their tours cost more than ones that can be purchased on shore, but they say the price difference has to do with factors including convenience, service and peace of mind.
"Our shore excursion program is designed as a turnkey operation, with a variety of excursions available, tickets delivered to guests' staterooms and roundtrip transportation provided between the excursion and ship," said Mico Cascais, Carnival Cruise Line's vice president of tour operations. "Since Carnival serves as facilitator between shore excursion operator and our guests, a number of costs are incurred, making a cruise line-booked excursion typically higher than an independently booked excursion."
John Stoll, Crystal Cruises' director of land programs, said that if you take the value proposition into consideration, the idea that cruise line tours cost more, "is probably more perception than reality."
"When you compare our tour programs with all the value-added components, I am not sure you are comparing apples to apples with the experience and/or the cost associated with our tours," he said. "Guests who book a Crystal Adventure can rest assured that we work with the most reputable tour operators possible, who through our agreements, provide insurance, and ensure the security and comfort of our guests."
One additional cost, said Bruce Krumrine, vice president of shore operations for Princess Cruises, is that the operators that work with the line are required to carry insurance that is valid in the U.S.
"Many foreign insurers will not provide this type of coverage, and therefore these tour operators have to purchase additional coverage from a U.S. insurer to be able to offer their products [to our guests]," Krumrine said. "This financial responsibility can also extend to port access, which requires background checks and security procedures to obtain access inside the secured port areas."
Krumrine said Princess' operators were "in constant contact with the shipboard management, so if a transport is delayed by traffic, plans can be made to delay the ship's departure."
Those factors, specifically safety and missing the ship, are the ones most often cited by cruise lines in explaining why passengers should book the lines' tour offerings.
Travel agents are divided about whether that is true, but the independent shore excursion providers say their tours are just as safe, just as insured and in some cases also guarantee a customer's return to the cruise ship.
Brad Miller, a former Royal Caribbean International and Celebrity Cruises executive who co-founded Shore Excursions Group, said his company incurs all costs associated with getting customers to the next port of call, should they miss their ship's departure from port. But that has never been necessary, he added.
"Our company is made up of people who have been in the cruise industry for a long time," Miller said. "None of us are aware of a situation where somebody on an independent, licensed tour missed a ship."
Tim Harwood, president of MyExcursions.com, said cruise lines might paint a "darker picture" of the independent shore excursions providers, but the operators he works with have many of the same insurance policies as the cruise lines.
"I can't get a helicopter seat in Alaska that doesn't have a $5 million liability, because cruise lines require it," he said.
Travel agents who use independent shore excursion providers say the companies are high quality. 
"My clients, many of them experienced cruisers, say the tours are usually the same quality as those offered by the cruise line," said Kenneth Tallent of Earthwinds Vacation Center in Charlotte. "Never have I had anyone miss the ship when using outside vendors."
Tallent said he thinks cruise lines use "scare tactics" to encourage passengers to book through the ships.
"My vendors guarantee they will have clients back to the ship in time for departure, so I don't worry about that aspect of the booking," he said. "The operators of the excursions have been working with the lines for years and know ship policies; many of them are the same companies the cruise lines use."
Tallent said that pricing for excursions booked outside the ship is comparable to the cruise lines' prices. The big difference, he said, is that independent operators offer options the cruise lines don't, giving Tallent's clients an "off-the-beaten-path option for their vacation."
He pointed to a couple who cruise the same itinerary every year, sometimes on the same ship, and look to Tallent to find new excursions for them each time.
"This way, they can travel in their comfort zone, knowing what to expect when arriving at a destination, but also know they are getting a new treat along the way," Tallent said.
Travel agents also say that independent tour providers often offer more customizable tours that allow for smaller, more intimate groups.
"Tours are private," said Tiffany Matthews Grant, manager of Signature's Destination Specialist program. "This provides a very VIP experience for the guests. Typically the tour is provided in the comfort of a luxury sedan, guests have the freedom to spend as much or as little time at a particular stop, there is no waiting around for other guests to finish, and [they have] the ability to chose a specific restaurant for lunch rather than having a set menu at a restaurant of the cruise line's choosing with 30 other people."
Matthews said working with the provider lets the agents customize the shore excursion.
"We definitely try and use our destination specialists for shore excursions," said Susan Reder, a Signature-affiliated agent with Frosh Classic Cruise and Travel in Woodland Hills, Calif. "The cruise lines do not give commission on shore excursions, and suggesting private shore excursions gives the client the personal service and a 'wow' experience and us the ability to make a profit for all our hard work."
Some cruise lines, specifically the higher-end lines, also offer customizable, private tours. With those tours, which can run into the thousands of dollars per person, the agents see too much commission left on the table.
Agents say it can take hours to help clients plan their shore excursions and tours during a cruise vacation, time they are not paid for if the tours are booked through the cruise line.
Independent tour providers say this is part of the reason their business is growing.
"I suspect more agents are turning to services like ours as this is a revenue stream that was not an option in days past," Harwood said. "It has been there for a time, of course, but it also requires agents to take initiative and work to suggest programs like ours."
Julie Karp, co-founder of ShoreTrips, said her company has been growing in the last five years from the "high single-figure increases, even in the recent recession years, to spectacular, mid-two-figure percentages."
ShoreTrips, she said, works with "smaller and more passionate outfits" on land, enabling repeat cruisers to experience something new.
"We feel that the ships have large audiences to entertain, and they are getting larger with each new ship," she said. "They do a wonderful job accomplishing that, but there are people onboard who want a smaller and more personal experience, and that is where ShoreTrips comes in."
Karp said she is baffled "by agents who will not take the time to offer a personalized activity."
Karp, Miller and Harwood all say they are just as thorough as the cruise lines when it comes to performing due diligence about the operators.
"We go to each destination, seeking the best, testing the guides, looking at equipment and collecting insurance policies," Karp said. "Our research is ongoing, and our quality is monitored constantly."
Still, not all agents direct their clients to work with outside vendors.
Dennis Bonade, a Cruise Planners agent in Margate, Fla., said that 90% of the time he tells his clients to book with the line.
"In today's climate around the world, with uprisings, strikes, crime, I explain to my clients all the things that can go wrong," he said. "[They could miss] the ship because of an excursion with a private vendor. Do the vendors have a license? Are their vehicles up to date on maintenance? How about the drivers?"
Bonade said the 10% commission ShoreTrips pays wasn't worth it to him.
He added that he sometimes helps clients book independently when they can save money.
"The only time I offer the alternative to the cruise lines is when they call on Alaska or Hawaii," he said. "Especially when a client wants to take a helicopter ride. They can save over $100 per person, [and] these states have strict laws governing their businesses and equipment."
So far, the cruise lines have not indicated any willingness to change their strategy of not paying commissions.
"Like most other cruise operators, Carnival does not offer commissions for third-party transactions such as shore excursions or spa treatments that are run by concessionaires or independent contractors," said Carnival spokesman Tim Gallagher.
Vicki Freed, senior vice president of sales for Royal Caribbean International, said there are occasions for agents to earn commissions on shore excursions.
Royal Caribbean and Celebrity Cruises will sometimes offer net rates for specially designed tours if 30 or more participants buy the excursion in advance, enabling the agent to mark up the excursion to earn a commission.
But in general, Freed said, "As much as we would like to pay commission on shore excursions for our travel partners, the reality is that we would have to increase the current pricing to add in commission, which would make the tour uncompetitive and increase the cost to the consumer."
Edie Bornstein, vice president of sales and marketing for Azamara Club Cruises, said Azamara also considers such requests for group excursions. She added that at some point, Azamara would like to alter its systems so that it can add such a fee to the final invoice as instructed by the agent.
MSC is the only major cruise line that offers commissions on shore excursions, when prebooked.
Most agents say they appreciate that MSC President Rick Sasso takes an agent-friendly slant, but ultimately they select the cruise line and itinerary based on the client.
Still, Sasso said that when MSC first began offering the commission, the line saw a huge uptick in the number of prebooked shore excursions but not necessarily in the shore excursions sold overall.
"What's good for us is being able to preplan," he said. "We do sell some more excursions in aggregate, because we know which tours have high interest."
Regent does not pay a commission on booked shore excursions, but many tours are complimentary to passengers once they are onboard and are folded into the cruise fare.
In that sense, agents are making additional commissions on shore excursions, though in small ways.
When asked earlier this year if this policy, which was part of Regent's elimination of most NCFs, spurred cruise sales, Frank Del Rio, CEO of Regent's parent company, Prestige Cruise Holdings, said he thought it did. In fact, he said that Regent's sister brand, Oceania Cruises, might add more commissionable parts to the cruise sale.
"If you don't have a happy sales force, your prospects aren't good," Del Rio said.
Bornstein did not rule out the possibility that Azamara might someday offer commissions on shore excursions.
"Anything is possible," she said, "especially if we consider this a strong motivation to selling the brand."
View a slideshow of some of the shore excursions being offered here.