Denver Sluice Viewing Area

The Denver Sluice sits just outside Wisbech, a proper feat of Victorian engineering that actually stops your mind for a second when you realise what you're looking at. Built in 1834, it's this massive brick structure straddling the River Great Ouse - designed to control water levels and prevent flooding in the Fens. You stand on the viewing area and watch the water either building up behind the gates or flowing through, depending on tide and rainfall. The whole thing is gloriously industrial and utterly unpretentious.

It's not a place where you'll spend hours - 20 minutes walking around and taking photos is realistic - but that's rather the point. Walkers and history types will find it genuinely interesting, particularly if you understand the precarious relationship between the Fens and water management. The viewing area itself is free and accessible, with decent sightlines across the sluice and down the river. Come when the gates are actually moving water and you'll see something tangible; come on a dead-still day and it's a bit of a static affair.

If you're based at Westerby Farm Camping and Glamping nearby, it's well worth the short drive as an afternoon stop rather than a dedicated trip. Pair it with a wander through Wisbech town centre - there's Georgian architecture worth your time - and you've got a decent few hours. Bring binoculars if you're a birdwatcher; the sluice attracts wildfowl year-round.