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Sometimes dinner is the outing. Schadau gives you a castle setting by Lake Thun, and a walk beside the water fits naturally before you sit down. It is an appealing change after days spent watching the clock for trains and cable cars.
Before booking, decide what you want most: a particular menu, a terrace or a clear lake view. Those are not automatically the same reservation. Ask about the table, current menu and dietary needs directly, and have an indoor plan if the terrace depends on the weather. Leave enough daylight to enjoy the setting.