Ballymagreehan Lough

Three miles of peaceful walking through Castlewellan Forest Park leads you to this proper hidden mountain tarn, tucked away in the shadow of Slieve Croob. The path isn't marked on most maps, which keeps the crowds away - though that also means you'll need decent navigation skills to find it.

What you get is a dark, still lough surrounded by heather moorland and rough grazing. It's not spectacular in a postcard way, but there's something deeply satisfying about having a whole lake to yourself on a quiet weekday. The water's too peaty for swimming, but it's a cracking spot for wild camping if you're properly equipped.

Walkers will love the sense of discovery here. Families with young kids might find the unmarked route a bit much, though older children who enjoy proper hiking will get a real kick out of the adventure. Photography enthusiasts come for the moody reflections, especially when mist rolls across the water in early morning.

Allow half a day for the round trip from Castlewellan, longer if you want to explore the surrounding hills. The nearby Tollymore and Castlewellan forest parks make this part of the Mournes brilliant for a walking holiday. Several glamping sites like Pine Tree Hollow and camping spots at Tollymore put you right on the doorstep of some proper mountain country.