The town centre is small and walkable. Beyond it, the network of Stagecoach buses serves most of the obvious onward destinations: the Borrowdale Rambler (78) runs south through Lodore, Grange, and Rosthwaite to Seatoller; the Honister Rambler (77/77A) is a one-way circular loop over Honister and back through Buttermere and Lorton; the X4/X5 run east and west on the A66.
For Derwentwater itself, the Keswick Launch from the pier is the right way to move — half-hour intervals in summer, less frequently in winter, with seven jetties around the shore. A day rover ticket pays off after two stops. Bike hire is available at several shops in town; the disused railway path to Threlkeld is the easiest local ride.