Ullswater's historic steamers are a memorable way to explore the lake. The various vessels include the stately Lady of the Lake, launched in 1877 and supposedly the world's oldest working passenger boat. The boats run east-west from Pooley Bridge to Glenridding via Howtown; tickets should be prebooked online.
A single fare from Pooley Bridge to Glenridding costs adult/child £9.85/5.90, so it's better value to buy the "all piers" pass, which stays valid for 24 hours and also gets you 50% off fares on the Ravenglass & Eskdale Railway.
If you're walking the Ullswater Way, you can also buy a five-day walker's ticket (adult/child £41.60/21.95).

