It was only mid-May, but the phone was ringing steadily at the front desk at Nebo Lodge on North Haven, a high-end boutique hotel and restaurant where food from an organic farm fills out the menu. The woman fielding the calls took pains to explain that visiting Nebo meant taking a ferry from Rockland, a 75-minute trip. And bringing a car is not recommended, she patiently added.

Though some of the public rooms still wore the look of winter, and a handyman was attending to repairs to the front parlor, callers were no doubt picturing something else—Nebo had just been featured in Bon Appetit, Travel & Leisure and Down East magazines, the articles beautifully illustrated with photos from the height of last summer.

The tourism industry is Maine’s largest, and though detractors like to dismiss its impact as being seasonal and supporting only service-oriented jobs, don’t tell that to the people whose paychecks and tips buy next winter’s heating oil. Along the coast, tourism—much of which is Mainers traveling from one part of the state to another—snarls traffic and clogs sidewalks. Detractors, again, are likely to refer to them as the “summer complaints.” But there really isn’t much to complain about when you consider that tourists, especially those from out of state, drop a lot of money here and don’t put great demand on services.

The island version of tourism is logistically difficult, as would-be visitors to Nebo learned. Each island has different amenities and travel challenges.

As lobstering faces an uncertain future, it makes sense now more than ever for islands to work toward diversifying their economies. As on the mainland, dollars left on the island recirculate through a community.

But how much tourism can islands sustain? State ferries and private boat services often are booked solid in the summer. If new lodging and restaurants are built or expanded, will septic systems be overly taxed? Will visitors clog up streets and waterfronts and make it more difficult for year-round residents do their work? Will the quality of life that draws people to these small communities itself by sacrificed?

The answers likely will vary from island to island. Some—like Peaks and Chebeague off Portland—have large inns that can host weddings and scores of guests. Others, like Swan’s and Isle au Haut, have limited overnight lodging options.

And then there are day-trippers—the ferry to Vinalhaven is like a poor man’s cruise through a beautiful part of Penobscot Bay, but if those visitors miss the last ferry back, will there be a room at the motel?

There’s another twist, too. Maine’s coastal towns and islands have seen a similar trend over the last 20 years, as rental cottages that used to host a different family each week have been purchased and upgraded for second homes. This trend may mean there is a niche for small, more modest motels that don’t have to be built to year-round standards.

Boaters stopping on islands for fuel, ice and food also represent tourism, as the family the runs the J.O. Brown Boatyard on North Haven, which just marked its 125th anniversary, knows.

When it comes to the islands, some serious questions about capacity and potential must be weighed. But sneering at the camera-wielding, sandal-wearing, bag-toting visitors walking down the middle of an island Main Street is not the right response. Direct them to a restaurant or art gallery, and remember that they are helping keep your friends and family in business.