Aldenham Country Park

The reservoir at Aldenham is what draws most people here - a proper working water body that's been part of Hertfordshire's landscape since Victorian times. You get a decent walk around the perimeter, which takes the better part of an hour if you're not rushing, with views across the water that genuinely lift the mood on a grey afternoon.

It's a decent spot for families with younger kids. The paths are manageable, there's usually waterfowl to spot if you're into that sort of thing, and it feels like proper countryside even though you're only just outside Borehamwood. Walkers will appreciate the peace of it - far enough from the main roads that you forget you're in southeast England. Birdwatchers might want to bring binoculars; I saw a few interesting species when I was there last.

The whole area works well as part of a broader day out in Hertfordshire. If you're staying at Home Farm Glamping just down the road, it's essentially on your doorstep. The Mimms Caravan Park is close enough that you could make it part of a longer walking route. What you won't find are crowds or facilities - this is stripped back and unglamorous, which is precisely the point.

Free to access as far as I can tell, and there's car parking near the entrance. Bring decent shoes if the ground's been wet; the path can get muddy. Worth a couple of hours of your time if you're in the area, though don't expect anything revolutionary - it's a nice walk, nothing more.