A 3km trail called Pot ob Rakah follows the Idrijca River Canal from the Kamšt (an 18th-century waterwheel used by the mines) to Wild Lake, a tiny, impossibly green lake fed by a deep karst spring. After heavy rains, water gushes up from the tunnel like a geyser and the lake appears to be boiling. With your own wheels, take the road out of town towards Ljubljana and turn at the sign to Idrijska Bela – it's 600m to the lake.
West of the lake, there's a footbridge and a river-swimming area, used in summer when the water averages about 20°C (68°F).
