The Borrowdale Valley south of Keswick is wonderful, with walks right into the heard of the Lakes, including Scafell Pike, which is England's highest mountain (a touch over 3,000 feet and not difficult to walk in decent weather). Borrowdale is one of my favourite places and Rosthwaite is a great base if you can get a place at the Royal Oak, the Scafell Hotel or the cottage where Prince Charles stayed a few years back.

For walking you should get both the Ordnance Survey map and Wainwright's famous guide to whichever area you are in. Wainwright is the walker's bible there, with every sheep track, wall and fencepost described (almost).

Ooops! Just saw you are only going for a day. What a mistake! You should spend at least a week, it's quite a big piece of countryside.