Zao’s Okama crater lake is one of Japan’s most spectacular volcanic phenomena — an almost perfectly circular caldera filled with water of an otherworldly emerald-green colour caused by dissolved sulphur compounds. The Zao Echo Line toll road reaches the rim, making this one of Japan’s most accessible volcanic craters, with the colour shifting between deep teal and bright lime with the weather.
🗓️ At a Glance
| Location | Zao, Yamagata (Miyagi border) |
| Hours | Echo Line ~Apr–Nov, daytime |
| Admission | Toll road fee applies |
| Time needed | About 1 hour |
| Best time | Summer–autumn; clear days for best colour |
What to See
- The near-perfectly circular emerald-green crater lake.
- The scenic Zao Echo Line toll road to the rim.
- Colour shifts between deep teal and bright lime.
- Panoramic volcanic scenery from the viewpoint.
Combine Your Visit
- Soak at Zao Onsen below.
- Pair with Yamadera on a Yamagata day.
- Read our Yamagata overview .
Getting There
- By car: the Zao Echo Line toll road (Apr–Nov).
- By bus: seasonal sightseeing buses from Yamagata City.
Tips
The Echo Line only opens roughly April to November (closed in snow). Clear, calm days give the most vivid emerald colour — check the weather before making the drive.
