Steamer, with walk or cycle back along south shore from Howtown.
Soooo many hills and walks – Aire Force is great, Hallin Fell a lovely wee walk up a ‘big’ mountain like hill, wander up to the Youth Hostel above Glenridding, Penrith Beacon etc. St Johns in the Vale – low and high rigg are lovely wanders.
Rent a canoe or boat from Glenridding sailing school.
Pedal – up onto the Cockpit, down to Howtown is an absolute (short) classic. More riding around that same area, easier bits over to Loadpot and down to Helton and Askham (big hill though…),
The mines at Mungrisedale (the Troutbeck one) are good for a wander and scrape round the old mine slag heaps in search of ‘crystals’ (old baryte mines).
Keswick pencil museum is a giggle on a wet day, the parks in Keswick and Penrith Castle are superb for that age. Good pools at Keswick and Penrith too.
(Maybe I have rose tinted specs, but one of the nicest places for a holiday in the UK, but then I am a Penrith boy…)