Hi,
It is possible to do the lake district by bus but it does need some planning !
On the trains the only railway line into the Lake District is a branch from the West coast main line (change at Lancaster) to Windermere. There is no rail line at Keswick. You can get back on the train at Penrith on the west coast main line which is to the east of Keswick on a bus route.
It is possible to do a few lakes in a day.
Options could include:
train to windermere, bus over the kirkstone pass to Patterdale / boat trip on ullswater (see link below).
Note on this route you don't visit Lake windermere (its a couple of miles down the road from the station..)
Option 2:
Train to windermere, bus to Keswick. Possible stop off at Ambleside or Grasmere. On this route you pass lake windermere, Rydal water, Grasmere, and Thirlmere reservoir on the way. There are nice walks around Grasmere lake.
Option 3:
get straight to keswick either via Windermere or Penrith and then go to Buttermere via the Honister pass ( bus service 77 77A ). Butermere is a good place to stop, nice walk around Buttermere lake. This takes in Derwent water, Buttermere, Crummock water + the Honister pass (steep single track road with very steep hills...)
I prefer the North Lakes than the Windermere area as its less busy.
I have not checked if these are doable in a day..
Bus time tables:
http://www.stagecoachbus.com/northwest/
If you click on the cumbria public transport map on the below web site, this will give you all the bus route numbers to look up on the stagecoach website:
http://www.cumbria.gov.uk/roads-transpor…
Different map show scenic bus routes etc: (you have to select bus routes down the right hand corner)
http://www.golakes.co.uk/maps/interactiv…
http://www.ullswater-steamers.co.uk/inde…