Slievenisky

The walk up Slievenisky isn't particularly long, but it's steep enough to earn your legs a proper workout. From Castlewellan, you're looking at a straightforward hike through moorland that rewards you with views across the Mourne Mountains and out towards Strangford Lough on a clear day. The summit itself is modest - don't expect dramatic peaks or dramatic anything really - but the surrounding landscape tells the story. You get a real sense of why this area matters to walkers.

Allow two to three hours for the round trip if you're not rushing. It's the kind of walk that appeals to people who actually enjoy walking rather than those after an Instagram moment - no crowds, no fanfare, just solid Northern Ireland countryside. Families with kids aged eight and up will manage it fine, though younger ones might find the ascent tedious. The path can be boggy in places, so proper footwear isn't optional.

If you're camping nearby - Slieve Croob Camping is barely over a mile away - this makes a cracking morning or afternoon outing. The peak sits right in the heart of the Mourne area, so you can easily string together a few walks across the region without moving your base. The climb itself is free, naturally, and there's nothing to book or arrange. Just turn up and go. Best visited in drier months when the ground isn't waterlogged, though honestly the weather here changes three times before breakfast.