You’re standing on the deck of a Casco Bay Lines ferry, the salt spray hitting your face, and Portland’s skyline is shrinking behind you. It’s a twenty-minute ride. That’s all it takes to feel like you’ve slipped through a crack in the timeline. Great Diamond Island Maine isn't your typical New England vacation spot with t-shirt shops and overpriced fudge. It’s quiet. Eerily quiet, sometimes, because there are no cars.
Most people heading out of Portland are aiming for Peaks Island because it’s the "popular" one. They want the golf carts and the crowds. But if you stay on the boat just a bit longer, you hit Great Diamond, and honestly, the vibe shift is immediate. It’s a mix of high-end luxury at Diamond’s Edge and the rugged, slightly overgrown ruins of a 19th-century military base.
You’ve got two very different worlds here. On one side, there’s the private residential community where people basically live in converted officers' quarters. On the other, you have the historic Fort McKinley site. It’s a place where the grass is perfectly manicured in some spots and hip-high in others. If you’re looking for a place to "see and be seen," this isn't it. If you want to disappear for a weekend and eat some of the best North Atlantic lobster while looking at a parade of sailboats, you’re in the right spot.
The Fort McKinley Factor: Living Inside History
Let’s talk about the elephant on the island. Fort McKinley.
Constructed between 1891 and 1907, this wasn't some minor outpost. It was a massive part of the Great Harbor Defense of Casco Bay. We’re talking about a site designed to house over 800 soldiers. During the Spanish-American War era, the government was terrified of a naval invasion, so they built these incredible brick barracks and massive gun batteries.
The cool part? They didn't tear them down.
In the 1980s, developers realized that these sturdy, beautiful brick buildings would make for insane real estate. Now, these former barracks are high-end townhomes. It’s a weird, fascinating blend of military rigidity and modern coastal luxury. You’ll be walking down a path and see a perfectly preserved battery where massive disappearing guns once sat, and right next to it, someone is sipping a Chardonnay on their patio.
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The batteries—like Battery Berry and Battery Honeycutt—are still there. They’re concrete giants. Explore them. You can feel the weight of the history. It’s not a museum where you’re behind a velvet rope; it’s just part of the landscape.
Getting Around (Or Why Your Legs Might Hurt)
There are no cars. I can't stress that enough.
Unless you’re a service vehicle or a specific island work truck, you’re walking, biking, or hitching a ride on a golf cart. This changes how you experience the island. You notice the smell of the pine needles more. You hear the birds. You also realize how out of shape you might be if you try to haul a week's worth of groceries from the ferry dock to the far end of the island.
- The Ferry: You’re at the mercy of the Casco Bay Lines schedule. Miss the last boat? Hope you like the island, because you’re staying there.
- Water Taxis: If you have the cash, Portland Express Water Taxi is the way to go for a private, "on your own time" arrival.
- Bicycles: Bring your own if you’re staying for a while. The island isn’t huge, but it’s big enough that walking everywhere gets old by day three.
Honestly, the lack of cars is the best thing about Great Diamond Island Maine. It forces a slower pace. You can’t rush. The island won’t let you.
Eating at the Edge of the World
If you’re a foodie, you probably already know about Diamond’s Edge Restaurant & Marina. It’s located in what used to be the fort’s power house.
It’s expensive. Let’s just be real about that. But sitting on that deck overlooking Diamond Cove at sunset? It’s hard to argue with the price tag. They do the Maine classics—clam chowder, lobster rolls, local oysters—but they do them with a level of polish you don't always find at a seaside shack.
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Pro tip: If the main restaurant is too formal for your mood, check out the Diamond’s Edge Market. It’s more casual, great for grabbing a sandwich before heading to one of the "secret" beaches.
The Beach Situation
Don't expect wide, sandy stretches like you’d find in the Outer Banks. This is Maine. The beaches here are pebbly, rocky, and tucked away in coves.
McKinley Beach is the go-to for many. It’s tucked into the cove, protected from the worst of the wind. The water is clear, cold enough to take your breath away, and perfect for searching for sea glass. You won't find thousands of tourists here. You might find ten people. Maybe fifteen.
What Most People Get Wrong About the Island
People think Great Diamond is entirely private. It’s a common misconception.
While a large portion of the island (the Diamond Cove side) is a private homeowners association with restricted access to certain amenities, the island itself is not off-limits. You can take the ferry, walk the public roads, visit the restaurant, and explore the historic fort areas.
However, there is a distinct "us and them" vibe sometimes between the seasonal vacationers and the year-round residents. It’s a small community. Everyone knows everyone. If you’re visiting, just be respectful. Don't wander onto someone’s porch thinking it’s part of the historic tour. It’s their living room.
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Another thing? The "Great" in the name is literal. It’s bigger than Little Diamond Island, but it’s still manageable. You can’t get lost for long.
The Logistics of a Visit
Planning a trip to Great Diamond Island Maine requires more thought than a standard road trip. You can't just "swing by" a CVS if you forgot your toothbrush.
- Pack Light, Pack Right: If you’re staying overnight at the Inn at Diamond Cove, they’ll usually help with your bags, but otherwise, you’re the pack mule.
- Groceries: There is no full-scale supermarket. If you’re renting a house, buy your supplies in Portland at Whole Foods or Hannaford before you board the ferry.
- Footwear: Leave the heels in the suitcase. The terrain is uneven, the paths are gravelly, and you’ll be doing a lot of miles.
- Connectivity: Cell service is surprisingly decent, but why would you want it to be? Put the phone away.
The Inn at Diamond Cove
If you aren't renting a private home, the Inn is your primary option. It’s built into the old soldier’s barracks. The rooms have massive windows and high ceilings. It feels grand in a way that modern hotels rarely do.
They have a pool, a cabana bar, and even a vintage bowling alley. Yes, a wood-lane, manual-pin-reset-style bowling alley. It’s charmingly old-school. It’s the kind of place where you spend the evening playing board games or sitting by the fire pit rather than scrolling through Netflix.
Nuance and Reality: It's Not For Everyone
I’ll be honest: if you hate bugs, you might have a rough time in the peak of summer. The Maine woods meet the ocean here, and the mosquitoes and "no-see-ums" don't care about your vacation plans. Bring serious bug spray.
Also, if you crave the neon lights and nightlife of a city, you’ll be bored out of your mind by 9:00 PM. The island shuts down. The silence is profound. For some, that’s heaven. For others, it’s a sensory deprivation tank.
Essential Island Activities
- The Art Gallery: There’s a small gallery on the island that showcases local Maine artists. It’s worth a stop to see how the local landscape inspires the work.
- Kayaking: The waters around the island are generally calm enough for a paddle, especially in the cove. Seeing the brick architecture of the fort from the water gives you a completely different perspective on the scale of the place.
- The "Moon" Walk: Walking the perimeter of the cove during a full moon is a local tradition. The way the light hits the old brick and reflects off the water is genuinely magical.
Actionable Steps for Your Trip
- Check the Ferry Schedule Twice: Casco Bay Lines changes their "runs" based on the season. A boat that exists in July might not exist in October.
- Book Dining Reservations Early: Diamond’s Edge fills up fast, especially on weekends when boaters from the mainland sail over just for dinner.
- Download Offline Maps: While there’s signal, the winding paths around the old fort batteries can be confusing. Having a GPS map that works without a hitch is a lifesaver.
- Visit Portland First: Spend your morning at the Old Port, grab your supplies, and take the mid-afternoon ferry. This gives you time to settle in before the sun goes down.
- Respect the "Private Property" Signs: The islanders are protective of their peace. Stick to the marked trails and public areas around the fort and the marina.
- Check the Weather: If a storm is rolling in, the ferry might be cancelled or delayed. Always have a "Plan B" for a night in Portland if the seas get too rough.