This glacial cirque lake makes a beautiful splash on a vast tract of forest. Lore has it that a king and nymphs dwell in its inky depths – and indeed the lake is pure Grimms' fairy-tale stuff. You can pedal across it by boat or stroll its shores. Should you want to ramble further, you can hike 1.5km up to Hornisgrinde (1164m), the highest peak in these parts, commanding far-reaching views over the rippling Black Forest from its lookout tower.