Nakasendo Trail's Hidden Blue River - Nagano's Best Summer Swim (Atera Valley)

Have you ever seen water so clear it looks photoshopped? 💧 This is Atera Gorge (Atera Valley) in Nagano's Kiso Valley — Japan's hidden emerald river and the BEST summer swim spot near the Nakasendo Trail.While international tourists crowd the famous Nakasendo post towns like Magome and Tsumago, this ice-cold, 15°C blue river is just around the corner and still completely under the radar. We took the family deep into the mountains to swim, dive, and cool off from the brutal Japanese summer heat.If you're hiking the Nakasendo Trail, this is a MUST-ADD stop right after your walk. It's the perfect activity for Nagano summer.