Talk

Cumbria isn't great for indoor things!
I don't really know the west coast that well and can't think of anything of hand
Indoor stuff tends to be smalll too so if you are going to drive anywhere make sure you have a couple of things in mind to do there.
Can't think of how far away you'll be from Penrith but Rheged is about the only place I can think of in Cumbria that will take a whole day!
Will have a think and get back to you

Thanks Nymphadora, I really appreciate that.

Have already found Carlisle castle, but I suppose if its a day good enough to go to the Castle, ds would probably more enjoy treasure hunting on the beach

Muncaster Castle is worth a look.
Ravenglass Eskdale miniature railway.

Great, thanks! . Might also drive down to blackpool for the day if we get really bored.

Theres lots to do
Allonby just down the coast from Silloth has great beach and dont forget a visit to ice cream shop for an Allonby Whopper!Actually really nice beaches most of the way down and also past seascale
Maryport Aquarium
Whinlatter Forest park nr Keswick
Grizedale Forest Park near Windermere
Tullie House Museum in Carlilse(opp castle)
Cars of the stars museum in Keswick
Walby farm Nr Carlisle
Trotters farm nr Keswick
Brockhole visitors centre nr windermere
The large lakes have ferries or you could hire a boat
I know some of thes are outdoors but have indoor bits to them
pencil museum is dull
There is also a climbing wall at keswick and you can hire bikes from the main tourist areas.

Animal Park at Dalton in Furness, really good for the kids!