Carn Brea mine (flooded)

An old tin mine flooded with rainwater - that's Carn Brea lake near Redruth, and it's one of those unexpected treats you stumble across in Cornwall that costs nothing and demands almost nothing of you either. The water's a murky green, ringed by heaps of industrial spoil and the skeletal remains of mining infrastructure. It's genuinely atmospheric if you like industrial archaeology; bleak if you don't. The walk around the perimeter takes maybe twenty minutes if you're ambling, less if you're just here for photos. Kids will find it interesting for about fifteen minutes - the abandoned feel appeals to that explorer instinct - then they'll get restless. For serious walkers or history types with a thing for Cornish mining heritage, this is worth the detour from Redruth. You get a sense of what tin extraction actually cost the landscape, and that's worth knowing. The lake itself doesn't offer swimming or boating - it's just there to look at and contemplate. There's no obvious visitor infrastructure, so go on a clear day if you want decent light. Free to visit, obviously. If you're camping at Lanyon Holiday Park or Little Menherion Glamping nearby, this is a solid half-hour outing that fills a quiet afternoon. Pair it with the walking trails across the moorland above and you've got a proper half-day expedition. Worth it mainly if you're genuinely interested in mining or looking for something off the main tourist trail.