Okama Crater Lake, Tohoku, Japan

Lake Locations:

Japan - Tohoku -

Also known as:  Goshiki Numa, Five-Color Pond

Okama Crater Lake is known as one of the world’s most beautiful crater lakes. Located in the caldera of Mount Zao, Okama welcomes visitors to this recreational and ecological park in the Tohoku region of northern Japan. Surrounded by 155 square miles of protected landscape that includes the entire Zao volcanic complex, Okama Crater Lake is the crown jewel of Zao Quasi-National Park on the border between Miyagi and Yamagata prefectures. Picture-perfect and displaying amazing changing colors, Okama Crater Lake is also known as Goshiki Numa, or Five-Color Pond. The highly-acidic, mineral-laden little lake changes colors due to mineral changes, often in conjunction with weather conditions. Created in the 1720s when the volcano erupted, the lake lies nestled among the barren domes and peaks of the complex volcano. Although currently dormant, Mount Okama is is the most active volcano in northern Honshu. That does not stop the many visitors from making this one of the main tourist attractions in the area.

Zao Quasi-National Park is highly popular as a hiking destination. There are three areas to the park: Zao North, Zao Middle and Zao South. The main hiking area, the ski area, and the lake are in Zao Middle or Zao Chou. Okama Crater Lake isn’t directly accessible, but some visitors do hike to the rim of the crater. Far more observe Okama from above; a skylift gives visitors an exciting view into the crater. A viewing point is also provided which offers an excellent vantage point for photography. There are no fish or vegetation in the lake due to its high sulfuric acid content. Active fumaroles around and within the lake regularly emit noxious gases, so a safe distance is recommended. Okama means ‘tea kettle’ in Japanese, and the small lake reminds observers of a small bowl of changing colors set within the caldera. With only 20 acres of surface area, scientists report the lake is about 90 feet deep, although other reports say 200 feet. Colors are best during the summer months as the lake freezes in winter. Winter in the area has its own attractions; Mount Okama area is one of northern Japan’s most popular ski and winter sports areas.

One of the nearby secondary peaks, Jizo-san, is the end of the Zao Sanroku Ropeway and holds a large statue of Jizo, the guardian of death spirits and the protector of travelers. The statue was erected in 1775 and today protects those who come to walk and play on Mount Zao’s slopes. The ski and snowboarding area is well-known for its tongue-in-cheek ‘snow monsters’ which appear in winter: small trees in warmer weather, winds carry water droplets off Okama Crater Lake in winter which coat the trees, forming weird shapes. The other end of the Zao Sanroku Ropeway is in Zao Onsen, a small resort town at the base of the mountains. Over a dozen hot spring resort and baths dot the base of the mountain, all heated naturally by hydrothermal springs. Some are only hot spring baths; the mineral waters are considered health-giving. Others are entire lodging, dining and resort complexes, with excellent accommodations and outstanding restaurants. Inns, pensions, lodges and small and large hotels can also be found here.

There are two ways to reach Okama Crater Lake and the resorts in the area. Driving the Zao Echo Line takes visitors between Miyagi and Yamagata prefectures. Mount Zao is the name of the entire small mountain range, and the Zao Echo Line was built to see it at its best advantage. One stop along the way is always the Akiu Great Falls near Takimidai Observatory. This overlook provides views of 594-foot high Sankai waterfalls and 107-foot high Fudo Taki waterfalls. Nearby are the Akiu Great Falls Botanical Gardens. There is also an excellent view of Okama Crater Lake from a viewing stop. A bus from Yamagata City takes visitors directly to Zao Onsen bus terminal in about 45 minutes. The Tourist Office near the bus terminal has information in English. Even indoor types coming to enjoy the hot springs usually take the Zao Sanroku Ropeway from town to the viewing point overlooking Okama Crater Lake. The chairlift runs every 15 minutes.

Okama Crater Lake can easily be a part of a larger visit to northern Japan. Yamagata City is famous for its cuisine and abundant seafood. The Hanagasa-matsuri Festival (flower-adorned hat festival) draws many visitors each year. The entire prefecture is filled with historic shrines and temples. The prefecture faces the Sea of Japan, with the Mogami River forming the Shonai Plain, home to rice farming. About 17% of the land in Yamagata Prefecture lies within national parks, and opportunities for outdoor recreations such as paragliding, skiing and trekking are abundant. It is no wonder that this area is a favorite vacation destination of so many Japanese city-dwellers. So, add Okama Crater Lake to your bucket list, and try to capture all five colors!

* Sources disagree on statistical information. Those listed here come primarily from a scientific study completed in 1988.

Things to do at Okama Crater Lake

  • Vacation Rentals
  • Hiking
  • Snowboarding
  • Waterfall
  • National Park

Okama Crater Lake Photo Gallery

Okama Crater Lake Statistics & Helpful Links

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Lake Type: Natural Saltwater Lake, Not Dammed

Surface Area: 20 acres

Normal Elevation (Full Pond): 5,151 feet

Maximum Depth: 90 feet

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A mesotrophic lake is slightly green and supports a moderate degree of plant and fish life. A lake's most desired trophic state is generally this mid-point - the mesotrophic state.

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1 acre-foot is equal to 325,851 US gallons. Siberia's Lake Baikal contains about 6,276,367,740,000,000 gallons of freshwater - nearly 1 million gallons for every living person on earth.

The other - and more widely used - measure of a lake's size is the lake's surface acreage. By that measure, the world's largest freshwater lake is North America's Lake Superior.


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