Zao Okama Crater Lake
An active volcano's crater lake that shifts between emerald green, milky turquoise and deep cobalt depending on volcanic activity and season. Called "Okama" (the iron pot) for its perfectly round bowl shape.
1–2 hours
Free
Eco-Line road: late Apr–early Nov; crater viewpoint always open when road is open
May–November (road open)
Drive up Zao Echoline from Yamagata City (approx. 1 hr); weekend/holiday bus from Zao Onsen (late April–early November only)
Location
Why Visit
- 1
The lake water is so acidic (pH 3.5) it corrodes metal — signs warn against touching the water
- 2
Colour changes from turquoise to green to opaque white within a single day depending on gases
- 3
The Zao Echoline mountain road passes directly by the crater — no hiking required
- 4
Combined with Zao Onsen below for a full-day volcanic landscape experience
Local Tips
The emerald Okama lake changes hue with weather and season. Come in May just after the road opens when surrounding snow remains and the contrast is dramatic. The drive up the Zao Echo Line through volcanic moonscape is itself spectacular. Combine with Zao ski area in winter.
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