On a budget, weigh it — Spree River Boat Tour isn't cheap for what it is.
~€19–25 (1 hr)
It's a genuinely restful, footsore-friendly way to see the central sights from the water, with cheap beer on deck and a running commentary. The catch: the commentary is often German-first or canned, departures clog with tour groups, and on a cold day the open deck loses its charm fast.