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The funicular takes you above Interlaken for views towards Lake Thun, Lake Brienz and the mountains beyond. For a shorter visit, make the viewpoint and a pause at the top the plan, then return to town. Leave time for the walk from the upper station and any queue.
Check the seasonal timetable, current operation and last descent before buying. Bring a layer for the top and shoes suited to the paths. Walking up from Interlaken is a separate mountain outing, not a substitute to improvise if you miss the last train.