The nearest rail station is Windermere, about 5 miles south; buses connect the station with Ambleside and continue toward Grasmere and Keswick. Drivers arrive from the M6 via Kendal and Windermere, but parking in Ambleside is tight on summer weekends.
Windermere Lake Cruises call at Waterhead, just below town, with boats to Bowness and Lakeside. It is a slow way to arrive, but a very good one.