Waterfront vs. Interior Across the Casco Bay Islands: Five Islands, Five Different Answers
On genuinely small islands like these, the usual waterfront-versus-interior question doesn't disappear, but it plays out at a different scale than it does on a mainland coastal town. Nearly every parcel on a small island has some relationship to the water simply by virtue of how little land there is -- but that doesn't mean the distinction between true shorefront or water-view property and a more interior lot stops mattering. This page covers the five other inhabited Calendar Islands of Casco Bay reached by Casco Bay Lines ferry from Portland -- Long Island, Chebeague Island, Great Diamond Island, Little Diamond Island, and Cliff Island -- not Peaks Island, which is already its own separate, larger market on this site with its own waterfront-vs-interior page. What follows is honest about where the distinction is real and where, on the smallest of these islands, it barely applies at all.
Long Island: A Landmass Thin Enough That Waterfront Proximity Is the Norm
Long Island's incorporated town has a total area of 33.52 square miles, but that figure is almost entirely water -- 32.10 square miles of it. The actual land area is just 1.42 square miles, with the main island commonly described as roughly three miles long and about a mile wide. On a landmass that thin, it is genuinely hard to be far from the shore in absolute terms -- most points on the island sit within a short walk of some stretch of water, which makes strict waterfront-versus-interior comparisons look different here than they would on a larger town.
That doesn't mean the distinction is meaningless. Direct shorefront property still carries different exposure, different views, and different maintenance realities than a lot set back from the water even by a street or two, and those differences are worth weighing on Long Island the same as anywhere else. What's different here is the scale: "interior" on a 1.42-square-mile island is a much smaller step away from the water than "interior" means on a bigger landmass, and buyers should calibrate expectations accordingly rather than assume an inland Long Island lot behaves like an inland lot on a much larger island or a mainland coastal town.
Chebeague Island: Large Enough to Have a Genuine Interior
Chebeague is the largest of these five islands, and its land area reflects that: 3.56 square miles of land within a 24.56-square-mile total area (the rest, 21.00 square miles, is water). Great Chebeague Island itself is roughly 1,930 acres, described as nearly five miles long and about a mile and a half wide -- meaningfully more landmass than Long Island's 1.42 square miles. That extra size means Chebeague genuinely has interior parcels that sit well away from any shoreline, in a way the smallest islands in this group simply don't have room for.
Even so, water remains close to the center of Chebeague's identity in ways that blur the line. The Great Chebeague Golf Club, a nine-hole course founded in 1920 and spanning roughly 28 acres on the island's north side, is described as having water views from every hole -- a small but telling illustration of how pervasive water proximity is even on the island in this group with the most room to be interior. For a buyer, that means Chebeague is the one island here where "I want an interior, non-waterfront lot" is a coherent, findable request rather than a near-contradiction -- but it's still an island where water is rarely far from view.
Great Diamond Island: Diamond Cove Asks a Different Question Entirely
Great Diamond Island complicates the waterfront-versus-interior framing in a different way. A large share of its developed residential property sits inside Diamond Cove, the gated, mostly private community built from the redeveloped Fort McKinley -- a coastal-defense post constructed roughly 1897-1906, eventually covering 111 acres with nine gun batteries, and listed on the National Register of Historic Places in 1985. Diamond Cove's homes are converted historic Army barracks and officers' quarters, not standard-built houses -- a residential character that is genuinely different from a typical shorefront-versus-inland comparison anywhere else on this site.
For a property inside Diamond Cove, the more meaningful question may not be waterfront-or-not so much as whether it sits within the gated, historically-converted development itself, with its own amenities -- Diamond's Edge Restaurant & Marina, the Diamond Cove General Store, and the Inn at Diamond Cove -- versus elsewhere on the island outside that community. This page does not have a confirmed land-area figure for Great Diamond Island, and a current, island-specific real estate value figure (ZHVI or median sale price) was not independently confirmed either, so no waterfront premium or typical-value number is stated here.
Little Diamond and Cliff Island: Two Very Different Kinds of Small
Little Diamond Island is, honestly, almost entirely a seasonal retreat rather than a year-round neighborhood. It had just 5 year-round residents at the 2000 Census, a figure explicitly attributed in part to the island's water supply being shut off in winter, which limits permanent habitation. A more recent commercial demographics snapshot shows an even smaller picture: 2 residents, 1 occupied household out of only 3 total housing units on the island (66.7% vacant). With numbers that small, there isn't much of a genuine interior market to distinguish from waterfront at all -- nearly the whole island functions as a private, seasonal waterfront retreat, and that thinness is the honest headline here rather than something to dress up.
Cliff Island looks similar in population size at first glance -- roughly 60 year-round residents as of the 2000 Census, swelling to about 200 in summer -- but functions completely differently day to day. It's the only year-round-inhabited island in this group with entirely unpaved roads, and residents get around by walking, bicycle, and golf cart rather than car. It has a real, organized civic and school life: a one-room schoolhouse, a 100-plus-year-old library, a historical society, and an all-volunteer community organization running the island's event calendar. Casco Bay Lines' own materials describe Cliff Island as "the smallest year-round inhabited island" in the bay -- a claim that sits in real tension with Little Diamond's even-smaller population figures above. That inconsistency isn't resolved here; it likely reflects the difference between Cliff Island's organized, year-round community and Little Diamond's near-empty, seasonal-retreat character, but both facts are stated honestly rather than picking one island to call definitively "smaller."
What the Real Estate Numbers Do -- and Don't -- Show
Two of these five islands have a confirmed, current typical-home-value figure from Zillow: Chebeague Island's ZHVI is $666,975, down 1.8% over the past year (as of data through June 30, 2026), and Long Island's ZHVI is $609,323, down 4.2% over the past year (as of data through January 31, 2026). Both figures are blended, island-wide numbers -- they cover the whole island's housing stock, not a waterfront-specific segment -- so this page does not state a waterfront price premium for either island, because no such figure was independently confirmed. Saying "waterfront costs X% more" without a real source behind it would be a guess dressed up as data, and that's not this page's approach.
No reliable, current ZHVI or median-sale figure was found for Great Diamond Island, Little Diamond Island, or Cliff Island. These are extremely thin, low-transaction markets -- Little Diamond has as few as 3 total housing units by one count -- where a handful of annual sales can make any "median" statistically meaningless, and inventing a number for any of them would do more harm than good. Anyone evaluating a specific property on any of these five islands should get a current, property-specific valuation, flood and insurance assessment, and title/access review directly from a licensed Maine real estate professional who works Casco Bay island properties, rather than relying on an island-wide average to price an individual shorefront or interior parcel. Nothing on this page is legal, insurance, or financial advice.
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Get a Free Agent Referral →Independent research. No ads. No sponsored listings. Land-area and population figures for Long Island and Chebeague Island are drawn from Wikipedia's entries on each island; Great Diamond Island's Fort McKinley and Diamond Cove history is drawn from Wikipedia's entries on Great Diamond Island and Fort McKinley (Maine); Little Diamond Island and Cliff Island population figures are drawn from Wikipedia and a commercial demographics aggregator (Point2Homes, methodology and vintage not independently confirmed), and Cliff Island's "smallest year-round inhabited island" claim is drawn from Casco Bay Lines' own island page. Real estate figures for Chebeague Island and Long Island are Zillow's own typical-home-value (ZHVI) data as cited above; no current ZHVI figure was independently confirmed for Great Diamond Island, Little Diamond Island, or Cliff Island, and none is stated. This page does not state a waterfront price premium, a specific count of waterfront versus interior properties, a land-area figure for Great Diamond, Little Diamond, or Cliff Island, or an insurance premium figure for any of these five islands -- none of those were independently confirmed, and readers should verify current, property-specific figures directly with a licensed Maine coastal real estate agent, an insurance professional, and each island's own town or the City of Portland's assessor's office before making a purchase decision. Peaks Island, the largest and most-populous Casco Bay island, is not covered on this page; readers interested in Peaks Island's own waterfront-versus-interior trade-offs, including its ferry-commuter dynamics, should see this site's dedicated Peaks Island pages. Nothing on this page is legal, insurance, or financial advice.