Fornah Gill Caverns

You'll need proper footwear and a torch for this one. Fornah Gill Caverns, just outside Settle in the Yorkshire Dales, is a proper underground adventure - the kind of place that reminds you why limestone country is so geologically brilliant. The caves themselves are modest by international standards, but that's partly their charm. You're not queuing past coach-loads of tourists; you're actually exploring rather than being herded through.

The caverns sit within a gill (a narrow valley, for those unfamiliar with Yorkshire geography), so you get the walk down to reach them as well. The passage opens up into chambers with the usual stalactites and stalagmites, and there's that particular damp coolness that caves always have - bring a jumper even in summer. Budget a couple of hours if you're doing this properly, including the approach walk.

This is genuinely good territory for families who can manage a bit of scrambling and aren't claustrophobic, and walkers will appreciate it as a diversion on a longer Dales ramble. Historians will find the glacial erosion patterns interesting enough, though there's not much in the way of archaeological drama here.

The nearest proper base is Settle itself, which has accommodation scattered about. If you're staying at one of the glamping pods or caravan parks within a few miles - Ribblesdale Pods, Malham, or The Dalesbridge - Fornah Gill works well as a half-day activity between longer walks. It's the sort of thing that takes an afternoon and gives you a decent story, without eating up your entire break.