Lee Valley Park

The Lee Valley stretches for miles along the Essex-Hertfordshire border, and this nature reserve near Waltham Cross is where the river actually feels wild rather than suburban. You get proper wetlands here - marshes, reedbeds, open water - which means serious birdwatchers turn up with their telescopes, but it's equally fine for a straightforward walk if you're after something greener than the usual park fare.

The reserve works best for people who don't need constant activity or manicured pathways. Bring binoculars and you might spot marsh harriers or water voles depending on season. The walking is gentle and flat, which is either a relief or a letdown depending on what you wanted. Families with younger kids do okay here for an hour or two, though there's nothing to keep restless teenagers occupied - it's genuinely just a nature spot.

Free to access, naturally. Allow a couple of hours for a proper circuit, though you can easily do half that if you're just poking about. Spring and autumn bring the most birdlife; summer feels a bit drowsy and overgrown.

If you're staying at Hertford Camping and Caravanning Club Site (6 miles away, and rated well), this makes a decent morning out before heading back for lunch. Lee Valley Caravan Park at Dobbs Weir is closer but smaller. The reserve doesn't stand alone as a full day's entertainment, but folded into a Hertfordshire break with other attractions nearby, it's a solid addition to the itinerary.