Mount Zao (Okama Crater)
Tohoku Region
Mount Zaō, located on the border of Yamagata and Miyagi Prefectures in Japan's Tohoku region, is a complex volcanic cluster known for its central volcano housing the Okama Crater lake. This crater lake, also called the 'Five Color Pond' due to its changing hues depending on weather conditions, spans 360 meters in diameter and reaches depths of 60 meters. Formed by a volcanic eruption in the 1720s, Okama is a major natural attraction offering breathtaking views. In winter, Mount Zaō is renowned for its frost-covered trees or 'juhyō,' which create ghostly 'snow monster' shapes due to freezing water droplets and snow accumulation. These formations are among Japan's three great frost-covered tree sites, attracting many visitors to the ski resorts with aerial lifts providing close access. The unique ecological conditions also support species like Rotaria rotatoria and Pinnularia spp. in the acidic crater lake. Mount Zaō thus combines geological wonder, ecological interest, and seasonal natural spectacles, making it a captivating destination year-round.
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Tip: The best time to witness the famous 'snow monsters' is mid-winter when frost-covered trees form spectacular shapes. Visitors are advised to check weather conditions before visiting and consider purchasing tickets for the Zaō Ropeway in advance to avoid long waits. Dress warmly and be prepared for cold, windy conditions at higher altitudes. Discounts may be available for groups or multi-ride passes at ski resorts. Early morning visits can offer clearer views of Okama Crater lake before afternoon weather changes.
Interesting facts
- •Okama Crater lake changes color depending on weather, earning the nickname 'Five Color Pond'.
- •Mount Zaō is one of Japan's 100 Famous Mountains.
- •The 'snow monsters' phenomenon is caused by freezing water droplets blown by strong winds that accumulate on trees, creating ghostly shapes.
- •Mount Zaō is part of the 'Three Great Frost-Covered Tree' sites in Japan alongside Mount Hakkoda and Mount Moriyoshi.
- •The acidic waters of Okama Lake host unique microorganisms like Rotaria rotatoria and Pinnularia species.
History
Mount Zaō is a volcanic complex formed through multiple eruptions, with the prominent Okama Crater lake created by an eruption in the 1720s.
Over centuries, the area evolved into a notable geological and recreational site.
Its ski resorts gained fame for the unique frost-covered trees phenomenon, recognized as one of Japan's three great 'snow monster' sites.
Climate change has recently impacted the frequency of this natural spectacle, marking a significant environmental change in the region's history.
Place Guide
Okama Crater Lake1720s
A volcanic crater lake approximately 360 meters in diameter and 60 meters deep, known for its striking color changes that vary with weather conditions. It was formed by a volcanic eruption in the 1720s and is the central attraction of Mount Zaō.
Frost-Covered Trees ('Juhyō')
These are trees covered with frost and ice formations created by freezing water droplets carried by strong winds from the nearby lake. They form ghostly, monstrous shapes called 'snow monsters' and are a major winter attraction at Mount Zaō.
Zaō Ropeway
An aerial lift operated by the ski resorts providing convenient access to the frost-covered tree viewing areas and scenic spots near the crater lake.