Hiratani Valley — Pristine Mountain Stream Walk

**Swimming season:** July–August, the second and third pools (20 and 35 minutes from trailhead) are swimmable — clear water maintained at 17–19°C by spring inputs. Bring a dry bag for valuables and waterproof sandals for the pool sections. **Autumn timing:** Late October, the valley walls turn gold and the leaf fall creates surface patterns on the pools. The best light for photography: 14:00–16:00 when the sun reaches the valley floor through the narrow upper opening.