Mudlarking on the ThamesBest for: ages 10+Trudging about in the mud by the river is a pretty cool pastime – but it’s also educational. If you keep your eyes peeled, you can uncover all sorts of gems washed up by the ebb and flow, from Victorian clay pipes and Georgian tiles to Mesolithic flints. Geocaching all over London, the UK and the worldBest for: ages 11+Who knew that looking for tiny containers in your local area could be so thrilling, and take you to places that you never knew existed? If you’re not up to speed, now is most definitely the time to discover geocaching. Download the Geocache app, and use GPS navigation and clues to unearth ‘treasure’ – this means anything from bottle caps to toy Smurfs, but finds can be more substantial.