You’ve probably seen it on Instagram. A tiny, lush island in the middle of a lake, almost entirely swallowed by a stone castle that looks like it was plucked straight from a Tolkien sketch. It’s McDermott’s Castle. Honestly, the first time you see it drifting on the waters of Lough Key in County Roscommon, it feels fake. Too perfect. Too moody.
But Ireland is full of these "aesthetic" ruins that actually have teeth. McDermott’s Castle isn't just a picturesque pile of stones for drone pilots; it’s a site that has been burned, rebuilt, fought over, and eventually turned into a "folly" by an eccentric family who wanted to spice up their view. Most people pull over, snap a photo from the shore of Lough Key Forest Park, and leave. They miss the real stuff.
What Actually Happened at McDermott’s Castle?
Let's get the history straight because the internet likes to romanticize things. The Mac Diarmada (McDermott) family were the dynastic lords of Moylurg. They ruled this patch of Connacht for centuries. This wasn't some weekend retreat. The island, known as Castle Island, was their primary residence from about the 12th century until the late 16th century.
It was a fortress.
Imagine living on a rock in a lake. It’s damp. It’s cold. But it’s incredibly hard to kill you. In 1184, lightning struck the castle. Imagine that. A direct bolt from the sky ignited the structure while the family was inside. According to the Annals of Loch Cé, a massive fire broke out, and many people died or drowned trying to escape the flames by jumping into the lake. It’s one of those grim historical footnotes that reminds you that medieval life was basically a series of unfortunate events punctuated by cool architecture.
The McDermott’s eventually lost the land in the 17th century during the Cromwellian conquests. The land passed to the King family (the Earls of Kingston). Now, this is where the "fake" part comes in. The castle you see today? It’s not the 12th-century original. Not really. In the 19th century, the Kings decided the ruin looked a bit drab. They hired an architect named John Nash—the same guy who worked on Buckingham Palace—to rebuild it as a "folly." They wanted a summer house that looked like a medieval castle.
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So, what you’re looking at is a 19th-century "re-imagining" built on top of the genuine medieval foundations. It’s a historical layer cake.
The Tragedy of Una Bhán
You can't talk about McDermott’s Castle without mentioning Una Bhán. It’s the Irish equivalent of Romeo and Juliet, but with more rain and more resentment. Una was the daughter of a McDermott chief. She fell in love with a boy named Thomas Costello, but her father wasn't having it.
He moved her to the island to keep her away from him.
Thomas used to swim across the lake just to see her. One night, he pushed it too far. The story goes that he tried to swim across, got exhausted, and drowned in the freezing waters of Lough Key. Una died of a broken heart shortly after. They are supposedly buried together on Trinity Island, another small island nearby. It’s a sad story, sure, but it adds a layer of weight to the site. When you look at those ruins at dusk, knowing the local folklore makes the silence of the lake feel a bit heavier.
Why People Get the Location Wrong
Lough Key is huge. It’s over 2,000 acres of water. If you just put "McDermott's Castle" into your GPS, you might end up on a random backroad looking at a cow.
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The best way to see it is through Lough Key Forest Park.
The park itself is built on the old Rockingham Estate. The main house of the estate burned down in the 1950s (fire seems to be a recurring theme here), but the grounds are spectacular. You’ve got tunnels, a massive observation tower, and "Moylurg Way" walking trails. But the castle remains the crown jewel.
Can you go inside?
Short answer: Generally, no.
Long answer: The island is private. Unless you have a boat or hire a local water taxi, you’re staying on the shore. Occasionally, local boat tours will take you close enough to see the masonry work, but the structure is unstable. Don't be that person who tries to climb the walls for a TikTok. The stone is crumbling, and the ivy—while beautiful—is basically holding the building together like a net.
How to Actually Visit (The Expert Way)
If you want the best experience, don't go at noon on a Saturday in July. It’ll be packed with families and dogs.
- Go at Sunrise: The mist hangs over Lough Key in the early morning. The castle looks like it’s floating in the clouds. This is when you get the "Discover-worthy" photos.
- Rent a Boat: There are boat rentals available at the Forest Park. Rowing yourself out toward the island (even if you don't land) gives you a sense of the scale that you just can't get from the pier.
- Explore the Tunnels: While you're there for the castle, don't miss the underground servant tunnels in the park. They are creepy, cool, and give you a glimpse into how the "other half" lived while the Earls were busy building follies on islands.
- Check the Weather: Roscommon is notoriously wet. If it’s pouring, the lake gets choppy and grey. Wait for a day with "broken clouds"—that’s when the light hits the limestone and makes it glow.
The Reality of Preservation
There is a lot of debate about what to do with McDermott’s Castle. Some want it fully restored into a museum. Others argue that its beauty lies in its decay. Currently, it sits in a state of "managed ruin." This means it’s being monitored so it doesn't collapse into the lake, but nobody is putting a roof back on it anytime soon.
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It’s expensive. It’s a logistical nightmare to get construction equipment onto a tiny island. And honestly? A perfectly restored McDermott’s Castle would probably lose its soul. There’s something haunting about the way the trees grow through the windows. It’s a reminder that nature eventually wins.
Essential Planning Details
If you're making the trip, Roscommon isn't exactly a tourist hub like Kerry or Galway. That’s a good thing. It feels more "real."
- Stay in Boyle: It’s the nearest town. It’s got a great abbey (Boyle Abbey) that is also worth your time.
- Eat Local: Grab a coffee at the park visitor center, but head into town for a proper meal.
- The Drive: It’s about 2 hours and 15 minutes from Dublin. Most of it is on the N4. It’s an easy day trip, but staying overnight allows you to catch that morning light.
Moving Forward with Your Trip
If you're planning to visit McDermott’s Castle, your next step should be checking the seasonal hours for the Lough Key Forest Park. While the park grounds are often open, the boat rentals and the Moylurg Tower access are seasonal, usually peaking between April and October.
Confirm your transport. If you don't have a car, getting to Roscommon is doable via Irish Rail to Boyle, but you'll need a short taxi ride to get to the lakeside. Pack waterproof boots; even on a sunny day, the lakeshore paths can be a boggy mess.
Focus on the history, respect the ruins, and take the time to look past the stone walls into the stories of the people who actually lived—and died—on that tiny piece of land.