Find out all the information you need about McDermott’s Castle here.
Majestic. Mysterious. Timeless. 

Seeing McDermott’s Castle on an island in Lough Key, County Roscommon, prompts those words to come to mind right away. With its green plants, old structures, and interesting stories, this place showcases the beauty of Ireland’s medieval age, where stories and history come together.

If you’ve ever dreamed of exploring an empty Irish castle on a lake island, McDermott’s Castle is a true-life adventure just waiting for you.

What Is the Location of McDermott’s Castle?

In the peaceful waters of Lough Key in County Roscommon stands McDermott’s Castle on Castle Island. The lake holds more than thirty wooded islets, and this island is one of them, adding charm and a mystical feeling to the area.

Because of its location, visitors here can take part in kayaking, boat rides, and photo excursions to discover Ireland’s lesser-known historic sites.

A Look into the History of McDermott’s Castle

As early as 1184, Ireland was divided into Gaelic kingdoms, and it was then that the origins of McDermott’s Castle began. It was built by the Mac Diarmada (McDermott) clan, one of the ruling families of the region, who held sway over this territory for more than 500 years.

Due to the island’s small size — barely 0.57 acres — the McDermotts also maintained a larger residence nearby, believed to have been at Moylurg Tower on the mainland.

Both its defensive role and its symbolic power made it important to the region. Then, in 1650, when Oliver Cromwell’s army took over Ireland by force, the English Crown seized the land, and the castle gradually fell into ruin — just like countless other Irish castles.

In the 19th century, the well-known Welsh architect John Nash added touches to the island’s ruins. Despite many years and harsh weather, the walls of the castle are still visible, marking the country’s many changes.

Legends and Love: The Story of Úna Bhán

No account of McDermott’s Castle is complete without describing Tomás Láidir’s love for Úna Bhán and the tragic outcome of their romance.

Úna, who came from a powerful chieftain’s family, fell deeply in love with a young man from a rival clan, Tomás Láidir. The relationship was kept secret because her father disapproved. Tomás used to cross the waters of Lough Key at night to meet Úna at the castle.

Unfortunately, one night during his journey, Tomás lost his life, and a desolate Úna died from heartbreak soon after. Tales from the area say that their ghosts still haunt the castle because of the love they shared and the tragedy that followed.

Some people claim that their spirits are still present, especially when the evening mist makes everything seem like a story or legend.

Visiting McDermott’s Castle | How and When to Go

While the castle remains largely abandoned and overgrown, it is a must-see landmark for anyone visiting County Roscommon. The best way to view the castle is by boat or kayak, both readily available at Lough Key Forest and Activity Park.

When to Visit:

• Spring and Summer (April–September): Best weather, lush green surroundings, ideal for kayaking and boat tours.

   

• Autumn (October): The surrounding woodlands of Lough Key Forest Park transform into a blaze of autumnal colours.

   

• Winter: Fewer crowds, but access by boat or kayak may be limited due to weather conditions.

   

For a truly special experience, visit at sunrise to see the castle looming in the mist above the water.

What to Check Near McDermott’s Castle

Even though the castle is the highlight, Lough Key Forest Park is not to be missed.

Highlights Include:

• Take an elevator or stairs to the top of the Observation Tower for stunning views over Lough Key and its islands.

   

• The Trinity Bridge and Wishing Chair are popular photo spots, thanks to their associated legends.

   

• Underground Tunnels and the Bog Garden offer fun and intrigue for those who love history and adventure.

   

• Zip-lining, biking on mountain trails, and boat rentals are great activities for a day out with family or friends.

   

Things About McDermott’s Castle You Might Not Be Aware Of

• The award-winning show Moone Boy included scenes filmed at the castle island, adding a modern twist to its old story.

   

• W.B. Yeats — one of Ireland’s most beloved poets — visited the island in 1890 and famously wished to purchase the castle to establish an art retreat. Sadly, this dream was never realised.

   

• The grave of Úna Bhán is said to rest on Trinity Island, another islet on Lough Key, adding another layer of intrigue for folklore enthusiasts.

   

Because McDermott’s Castle is one of only a few island castles left in Ireland, it holds significant value in the country’s heritage.

Finally

McDermott’s Castle not only stands as a ruin but also as a place to explore stories of love, loyalty, betrayal, and strength from ancient Ireland. Whether you enjoy history, romance, or exploring new places, this fortress won’t disappoint.

In the future, if you’re around County Roscommon, set aside some time, rent a boat, and travel out to Castle Island. Perhaps, you’ll catch a glimpse of Úna and Tomás, who still seem to wander in the fog.