What you're actually getting on this walk
The Comber Greenway is the old Belfast and County Down Railway line, now a shared path for walkers, runners and cyclists that runs out of East Belfast through Dundonald and on towards Comber. For a dog, the appeal is obvious: it's flat, mostly traffic-free once you're on it, and long enough that you can do a short loop near a car or commit to a proper stretch of it without ever crossing a busy road underfoot.
It's also one of the most searched dog walks near Belfast for a reason — it suits dogs that don't love uneven ground, older dogs, and owners who want a predictable, sheltered route rather than an adventure. But because it's an old railway line, it was built to avoid water, not to run alongside it. That matters a lot if swimming is part of why you're going.
Where the water actually shows up along the way
For long sections between Belfast and Dundonald, there's no open water anywhere near the path — you're walking an embankment or a cutting, with gardens, fields or retail units either side. Don't go expecting a riverside walk the whole way; it isn't one.
Water turns up at specific points. Near Dundonald, close to Billy Neill Country Park and the Lough Moss leisure centre, there's a pond that some dogs will clock from the path. Further on, as the greenway comes into Comber itself, you're close to the Enler River, which runs through the town and historically fed the old mill. This is where most of the real water decisions get made on this route — not out on the open embankment.
Where a dog can reasonably get in
If your dog is a keen swimmer, the calmer, shallower stretches of the Enler on the approach to Comber town are generally the more forgiving option, well away from any weir or sluice structure. Look for a sloped, visible bank rather than a steep drop, and always check how the water's running that day — after heavy rain even a usually gentle stretch can be running fast and brown, and that's not the day to let a dog wade in.
Treat the Lough Moss pond near Dundonald as a look, not a swim. It's an amenity pond close to a leisure centre and country park rather than a wild swimming spot, and in warm weather ponds like this are exactly the kind that can carry blue-green algae, which is genuinely dangerous to dogs. If the water looks scummy, green-tinged, or there's any sign warning about algae, don't let a dog near the edge, never mind in.
Where they should not go near
The one spot worth being properly firm about is the weir area on the Enler close to Comber town. Weirs look tame from above and are anything but — the water below one moves faster than it looks, the stonework is slippery, and dogs that jump in chasing a ball or a scent can struggle to get back out against the pull. This is a stretch to keep dogs on lead and well back from the edge, not just off lead and 'probably fine'.
In winter, be wary of the low, flat puddles that sit on and beside the path after a hard frost or heavy rain — some conceal old ballast, broken edging or potholes from the original railway, and a dog running full tilt through what looks like a shallow puddle can come down awkwardly. And if you're walking in summer, any pond or slow backwater with a greenish sheen on it is one to skip entirely, no matter how hot your dog is.
Where to park and which end is quieter
At the Dundonald end, there's generally parking near Billy Neill Country Park and the Lough Moss leisure centre, which also gives easy access onto the greenway itself — this tends to be a calmer starting point than piling straight in from the Belfast side. The Comber end, near the town, is handy if you want to finish with a coffee, but it gets busier on market days and weekends, so expect more prams, cyclists and other dogs around the entrance.
Closer into East Belfast, access points near Knock and further along towards Sydenham put you onto a much more urban stretch of the path, useful if you just want a short, flat walk rather than the full run out towards Comber. Whichever end you start from, it's worth checking current signage at the entrance, since access points and any temporary closures can change.
What February actually does to this path
The tarmac surface drains reasonably well compared with a muddy field walk, which is part of why it's popular in a Northern Ireland winter. But the old railway cuttings — the sunken, tree-lined sections — hold shade and damp for longer than the open embankment stretches, and these are the bits that ice over first on a sharp frost morning and stay greasy longest afterwards.
The verges either side turn soft and muddy through winter even when the path itself is fine, so if your dog likes to range off the tarmac for a sniff, expect muddy paws and a reasonably dirty coat by the time you're back at the car. Wind is the other factor — the cutting sections funnel it, so a day that feels calm at the car park can feel a lot sharper once you're down in the trench of the old railway line.
Leads, bikes and the road crossings
This is a shared path, and cyclists use it properly — commuters, families, the lot — so a dog that lunges or startles at a bike needs to be on a lead here, not just under loose voice control. Several roads cross the greenway along its length, usually with barriers or gates to slow both bikes and dogs down, but barriers aren't a substitute for a lead at the actual crossing point.
Towards the Comber end, you're coming closer to farmland at points, so keep an eye out for livestock in adjoining fields even where you can't see them clearly from the path — a dog under control there is a dog that stays welcome on a route that a lot of local farmers and walkers share.
After a wet walk
If your dog has been in the river near Comber or come off the path through mud, a decent towel-down before they get back in the car saves a lot of bother, and it's worth rinsing paws if you suspect any algae contact, even a brush past the edge of a pond. A dog that's had a proper outdoor session like this usually settles well afterwards, which is exactly the kind of day we aim to give dogs staying with us for day care or boarding at Johnny's Doggy Hotel — tired, clean enough, and happy.