Ōnuma Pond
大沼池
The largest lake in Shiga Kōgen. Its acidic volcanic waters glow cobalt blue and emerald green, and legends of a black dragon surround it. It is the classic destination for lake hikes in the highlands.
Ōnuma Pond is the largest of dozens of lakes and marshes on Shiga Kōgen. It has a circumference of about 3.5 kilometres. Acidic compounds from volcanic activity give its water a striking cobalt blue and emerald hue, which is most vivid on sunny days when viewed from the slopes above. In autumn, the lake is framed by the red and yellow foliage of larches and beeches. On the lakeshore stands the Ōnuma Shrine, which honours the legend of a black dragon, and a Great Serpent Festival is held there every summer. No road reaches the lake directly. The most common route is to walk about one hour along a forest path from the "Ōnuma Entrance" bus stop to the lake, a round trip of about 2.5 hours. Fit hikers can take a loop of about five hours past Mount Shiga and the Forty-Eight Ponds. There are no shops around the lake, so bring your own water. Bears are present on some trails, so hike in a group and carry a bear bell.
Opening hours
Open all day (closed in winter due to snow)
Nearby sights
- Shiga Kōgen
- Higashidateyama Alpine Botanical Garden
- Mount Yokote
- Jigokudani Monkey Park
- SORA terrace (Ryuoo Ski Park)
- Shibu & Yudanaka Onsen