Seasonal Recreation on Casco Bay: Long, Chebeague, Great Diamond, Little Diamond, and Cliff Island by Season
This page covers Long Island, Chebeague Island, Great Diamond Island, Little Diamond Island, and Cliff Island -- five genuinely separate Casco Bay communities, each reached by Casco Bay Lines ferry from downtown Portland, each with its own version of the same underlying pattern: a dramatic summer surge followed by a real, quiet off-season. Peaks Island, the largest and most frequently served of the Calendar Islands, already has its own dedicated seasonal-recreation page on this site covering its year-round commuter-neighborhood rhythm in depth; this page doesn't restate that content, and readers wanting Peaks Island specifics should go there instead. What follows here is the seasonal pattern for the other five islands, each of which swells with a seasonal population many times its year-round base, then empties out again -- honestly, and without inventing visitor counts, water temperatures, or specific dates that weren't independently confirmed in the research behind this page.
Summer Is the Season, By a Wide Margin, on All Five Islands
Summer is dramatically the peak season across Long Island, Chebeague Island, Great Diamond Island, Little Diamond Island, and Cliff Island, and the population numbers make the point better than any description could. Long Island's year-round population of 234 (per the 2020 Census) swells to roughly 800 to 1,000 in summer -- three to four times its off-season base. Chebeague Island's own population grows from 396 year-round residents (per the 2020 Census; Casco Bay Lines' own island page separately cites "over 360 year-round" residents) to more than 1,600 in summer, more than tripling. Great Diamond Island, Little Diamond Island, and Cliff Island each see a similar seasonal surge in their own way -- Cliff Island's roughly 60 year-round residents grow to roughly 200 in summer, and Great Diamond and Little Diamond, though their exact current year-round counts are genuinely unresolved between older Census figures and more recent commercial snapshots, are both understood locally as summer-heavy communities built around a much smaller committed year-round core.
That summer surge is what powers the handful of real, named businesses and activities each island actually has. On Chebeague, that means dinner at the Chebeague Island Inn, a round at the Great Chebeague Golf Club -- a nine-hole course founded in 1920 with water views from every hole and a clubhouse that's a repurposed circa-1807 residence, listed on the National Register of Historic Places in 2015 -- and casual kayaking and boating in the calm water around the island. On Great Diamond Island, summer is when Diamond's Edge Restaurant & Marina and the Diamond Cove General Store see their real business, serving the redeveloped former Fort McKinley grounds now known as Diamond Cove. Kayaking and boating around all five islands are genuinely summer-driven activities, tracking the same seasonal pattern as the population itself.
Little Diamond Island: Functionally a Summer-Only Retreat
Little Diamond Island is the clearest case in this group of a place whose recreation calendar and its population calendar are the same thing. The island's water supply is shut off in winter -- a real, physical limit on year-round habitation, not a lifestyle choice -- and its year-round population is correspondingly tiny (5 residents at the 2000 Census; a more recent commercial demographics snapshot shows as few as 2). That means there is essentially no meaningful off-season activity to describe on Little Diamond: it functions almost entirely as a summer and seasonal retreat, with its handful of privately owned cottages occupied when the water is on and largely empty once it isn't.
This page won't invent a boating scene, a dining option, or an off-season community life for Little Diamond that the research behind this page didn't find -- honestly, none of that exists there in any meaningful way. Anyone drawn to Little Diamond should plan around its identity as it actually is: a warm-weather retreat, not a year-round recreational destination.
Cliff Island in Summer: Golf Carts, Bicycles, and a Walkable, Unpaved-Road Character
Cliff Island's defining physical trait -- it's the only year-round-inhabited island in Casco Bay with entirely unpaved roads, where residents and visitors get around by walking, bicycle, and golf cart rather than by car -- is at its most active and most walkable in summer, when the island's small, real amenities are actually open. That includes a 100-plus-year-old island library, a tennis court, a baseball field, and a playground, plus a Historical Society museum that operates summers only. The island's active, all-volunteer "ACE" organization -- covering athletics, conservation, education, arts and crafts, and entertainment -- runs much of the island's event calendar out of the Cliff Island Association Hall, which completed a renovation in 2020.
Cliff Island's own year-round population of roughly 60 grows to roughly 200 in summer, and that seasonal population is what fills the island's unpaved lanes on foot, by bike, and by golf cart during the warm months. This page won't claim a specific summer visitor count or event schedule beyond what's described generally here -- confirm current programming directly with the island's own community organizations before planning around it.
Fall and Winter: A Dramatically Quieter Bay, With Two Islands That Keep a Real Community Going
Once the summer population departs, all five of these islands get dramatically quieter -- Long Island's population drops back toward its 234 year-round base, Chebeague's back toward the 300s, and the same pattern holds for Great Diamond, Little Diamond, and Cliff Island. Casco Bay Lines' own current rates page defines a peak season (April 18 through October 12, 2026) and a separate, lower-priced off-peak season (October 13, 2026 through April 16, 2027) for its passenger fares, which reflects the same underlying seasonal reality from the ferry operator's own side -- typically, service and demand both scale down in the off-season, though the specific current schedule should be verified directly with Casco Bay Lines rather than assumed from this page.
Chebeague Island and Cliff Island are the genuine exception to an otherwise quiet off-season, and it's worth stating plainly: both islands retain a real, if small, year-round community and school life through the winter months, unlike Little Diamond Island. Both maintain their own tiny on-island elementary schools -- Chebeague's is described as a two-room schoolhouse, Cliff Island's a one-room school, both serving pre-K through 5th grade, with older students commuting daily by ferry to mainland Portland-area schools. That means winter on Chebeague and Cliff Island isn't emptiness; it's a quieter, genuinely local version of the same place, with year-round residents, a functioning school, and island institutions like Cliff Island's library and ACE organization continuing to operate at a smaller scale. Long Island likewise maintains its own year-round Long Island School. Great Diamond Island and Little Diamond Island, given their small and heavily seasonal populations, were not found to have a dedicated on-island school of their own.
Spring: Ferry Schedules and Seasonal Businesses Ramp Back Up
Spring on these five islands is the ramp-up period rather than a season with its own distinct recreational identity -- ferry schedules and the islands' small roster of seasonal businesses typically build back toward summer capacity ahead of the warm-weather surge. On Chebeague, that includes The Niblic, the coffee-and-sandwich spot at the Chebeague Island Boat Yard, reopening for the season. On Cliff Island, it includes the Cliff Island Store & Cafe -- the island's evident sole dining option -- coming back online after a quieter winter.
This page won't state a specific reopening date for any seasonal business or a specific spring ferry timetable, because those details change year to year and weren't independently confirmed for a current season in the research behind this page. The honest, general pattern is enough to plan around: spring is when these islands' thin, seasonal business rosters and ferry capacity both begin scaling up, not when they're already at full summer strength.
What This Means Before You Decide
Put together, honestly: recreation on Long Island, Chebeague Island, Great Diamond Island, Little Diamond Island, and Cliff Island has one dominant seasonal shape, with two real variations worth knowing before you buy or move. The dominant shape is a dramatic summer surge -- population multiples of three to four times or more on every one of these islands, filling the small, real, named businesses and amenities each island actually has -- followed by a much quieter fall and winter. The first variation is Little Diamond Island, which is functionally a summer-only retreat with essentially no off-season activity at all, driven by its own winter water shutoff. The second is Chebeague Island and Cliff Island, both of which keep a genuine, if small, year-round community and school life going through the winter, unlike Little Diamond -- a real distinction worth understanding rather than assuming every one of these islands goes fully dormant once summer ends.
None of this is medical, legal, or relocation advice, and nothing here should be read as a current ferry schedule, business hours, or event calendar. Verify current Casco Bay Lines schedules and seasonal business hours directly before planning a visit, purchase, or move, and talk to current island residents about what a specific season actually feels like on the island you're considering, rather than assuming either the summer crowds or the winter quiet is the whole story. Readers whose interest is specifically Peaks Island should use this site's own dedicated Peaks Island seasonal-recreation page, which covers that island's year-round commuter-neighborhood rhythm in depth.
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Get a Free Agent Referral →Independent research. No ads. No sponsored listings. Year-round and summer population figures for Long Island (234 year-round per the 2020 Census, swelling to roughly 800 to 1,000 in summer) and Chebeague Island (396 year-round per the 2020 Census, with Casco Bay Lines' own island page separately citing "over 360 year-round" and "more than 1,600 summer" residents) are per Wikipedia and Casco Bay Lines' own island pages. Cliff Island's population (roughly 60 year-round, roughly 200 in summer) is per the 2000 Census as cited by Wikipedia and Casco Bay Lines. Current year-round population figures for Great Diamond Island and Little Diamond Island are genuinely unresolved between older Census figures and more recent commercial demographic snapshots and are not restated as settled here. The Great Chebeague Golf Club's 1920 founding, its circa-1807 clubhouse, and its 2015 National Register listing are per Wikipedia. Diamond's Edge Restaurant & Marina and the Diamond Cove General Store are per Diamond Cove's own amenities page. Little Diamond Island's winter water shutoff and tiny population are per Wikipedia. Cliff Island's unpaved-road, walking/bicycle/golf-cart character, its library, tennis court, baseball field, playground, Historical Society museum, ACE organization, and 2020 Association Hall renovation are per the Island Institute's community profile for Cliff Island. School detail for Chebeague and Cliff Island is per the Island Institute's community profiles. The Niblic (Chebeague Island Boat Yard) and the Cliff Island Store & Cafe are per Casco Bay Lines' own island page and the Cliff Island Store & Cafe's own site, respectively. Casco Bay Lines' current peak season (April 18 through October 12, 2026) and off-peak season (October 13, 2026 through April 16, 2027) fare windows are per the carrier's own passenger rates page. This page does not state a specific current visitor count, water temperature, seasonal cutoff date, ferry schedule, or business reopening date beyond what's described generally above, and it deliberately does not restate Peaks Island's own seasonal-recreation content, which belongs to this site's own dedicated Peaks Island page. Always confirm current schedules, fares, and business hours directly with Casco Bay Lines and each island's own businesses or community organizations before making a visiting, moving, or purchase decision. Nothing on this page is medical, legal, or relocation advice.