Hadleigh Castle Country Park

The ruins of Hadleigh Castle sit on a proper steep hill overlooking the Thames estuary, and on a clear day the view across the water is genuinely striking. It's a country park now, so you're walking through managed grassland and woodland with the medieval remains as the focal point - not a full-on historical site with interpretive boards, more a case of scrambling up to the broken walls and making your own sense of what was once here.

The walk itself is the real draw. From Benfleet, it's accessible enough without being a trudge, and there's something satisfying about the climb - your lungs know you've done something. Once you're up there, the panorama opens up nicely: industrial Thames on one side, greenbelt on the other. Walkers will get the most from this, honestly. Families with younger kids might find the 15-20 minutes up fairly steep, and there's not much to occupy them once they reach the top beyond the basic "look, old castle" moment. Bring proper shoes.

It's free to enter and you can spend as long as you like - though realistically an hour covers it unless you're the type to sit and sketch or photograph for ages. The whole thing plays well into a long weekend at Haven Kent Coast Holiday Park near Canvey Island, giving you decent coastal variety without straying far. Go on a weekday morning if you can; weekends get busier and the estuary views lose some magic with the crowds.