Tanygrisiau Reservoir

The water sits still as glass most days, hemmed in by steep slate hillsides that rise like walls on either side. Tanygrisiau Reservoir, just above Blaenau Ffestiniog, is one of those quiet Welsh landscapes that doesn't announce itself - you have to actually seek it out.

It's a working water supply, so don't expect funfairs or facilities. What you get instead is a proper walk through upland terrain, with the reservoir itself forming the centrepiece of a circuit that takes between 90 minutes and two hours depending on your pace and how often you stop to look around. The views from the eastern bank are the strongest - you can see across the water to the old slate workings that carved up these hills for centuries. On a clear day, it's genuinely absorbing.

This works best for walkers and landscape photographers. Kids might manage it, though the path gets boggy in places and there's nothing here to break up the walk - no café, no visitor centre, no distractions. Families with younger ones often find it a bit relentless.

Cae Du Campsite, six miles south near Dolwyddelan, or Llechwedd Glamping closer by at Plas Weunydd, both serve as decent bases if you're combining this with exploring the wider Ffestiniog area. The town itself has the slate mine tours and the narrow-gauge railway if you need other options. Free to visit, best tackled in decent weather - mist rolls in fast here and suddenly it's all rather dull.