Hemel Hempstead Sports Centre (Everyone active)

The Sports Centre sits right in Hemel Hempstead town centre, run by Everyone Active, and it's the sort of place that actually delivers on what it promises - a proper working leisure facility, not some tired relic. Inside you'll find a swimming pool, gym, sports halls, and various classes. The pool is decent for lengths or splashing about with kids. The gym side is standard fare - treadmills, weights, classes - but the changing facilities are clean and the staff know what they're doing.

It's honestly best suited to people who want to either train seriously or keep the kids entertained on a rainy day. If you're camping at Fuzzy's Farm just down the road (1.8 miles), it's handy for burning off energy without having to drive far. Highridge Farm's shepherd huts are only 3.4 miles away too, so within easy reach if you fancy a proper swim after a day outdoors.

Admission costs vary depending on what you're doing - casual swimming, gym passes, or class drop-ins all price differently, so check their website before you go. It's not somewhere to linger for hours, but as a supplement to a park-based holiday in Hertfordshire, it works well. Go early morning if you can, especially weekends, when it's less rammed with school groups. Nothing glamorous about it, but that's rather the point.