[Ashoro Town] The five colors of Lake Onneto

About 20km southwest of Akanko Onsen, Onneto is a small lake, about 2.5km around. The map shows it inside Ashoro Town, Tokachi, but it lies inside the Akan-Mashu National Park next to Akanko Onsen, and is under the shadow of Mt. Meakandake.
As its nickname "Lake of Five Colors" says, the lake is famous as its color appears to change with the season or even hour. Clear blue, emerald green, dark blue, and more...all who see the water's changing colors are fascinated.
From the wooden viewing platform jutting from the water's surface, you can see Meakandake to the left and Akanfuji to the right. On windless days, these mountains are reflected in the water like a mirror. Autumn leaves reflected in the blue water are a truly beautiful sight. The climbing path entrance for Meakandake is nearby, as well.

The secret to Onneto's changing colors... Is it the sunlight and Meakandake's shadow?

So why does it appear that Onneto's color changes with the season and hour?
There's no clear explanation yet, but most think it has to do with Mt. Meakandake.

Onneto was formed when an eruption of Meakandake blocked the Rawan river. This led to water growing acidic due to effects from the volcanic gases and water running from Meakandake, which is still active.

So with this background, what's the reason for the colors changing? As the sun's radiation shifts with time, it changes the levels of minerals dissolved in the water. The interaction between these two conditions could explain the change of color people see in the water. Whatever the reason, the secret of the colors is a wonderful natural phenomenon.


◆How to get from Akanko Onsen to Onneto
Rental Car: Take National Highway 241 west about 6km, then turn left toward Obihiro. After 7.4km follow the sign and turn left, then go 6.6km ahead. (Closed in winter).
◆How to get from Akanko Onsen to Ashoro Town　
Rental Car: Take National Highway 241 west about 6km, then turn left toward Obihiro and go 48km ahead.

◆For information about Ashoro Sightseeing:
NPO Co. Ashoro Tourist Association　Kita 1-jo 1-chome, 1, Ashoro Town. Inside Michi no Eki Ashoro Ginga Hall 21 Tel: +81-156-25-6131

Feel the origins of the Earth at Onneto Hot Falls. A Scientist's dream!

If you walk 3km deeper in from Onneto, you'll find the secret of secrets... Onneto Hot Falls! Here, hot spring water flows down a 50m cliff, and this spot is the world's only verified above ground source of Manganese Dioxide ore. Manganese dioxide ore deposits are usually only found on sea beds or in former sea beds, so Onneto Hot Falls is quite rare, and so designated as a national natural monument.
So how is manganese dioxide Ore made here? The key is in the hot spring waters. Specific microbes have been found in the water here. Those microbes work with primitive algae to create manganese dioxide ore. Microbes making ore! This mechanism is a phenomenon that began 3.5 billion years ago, during the Precambrian era. In other words, Onneto Hot Falls offers an invaluable clue to the very origins of the world.

When you see the lustrous black manganese dioxide ore on the rock face, you are looking back on the ancient source of the seas, of oxygen, of all life on earth.


◆How to get from Akanko Onsen to Onneto
Rental Car: Take National Highway 241 west about 6km, then turn left toward Obihiro. After 7.4km follow the sign and turn left, then go 6.6km ahead. (Closed in winter).
◆How to get from Akanko Onsen to Ashoro Town　
Rental Car: Take National Highway 241 west about 6km, then turn left toward Obihiro and go 48km ahead.

◆For information about Ashoro Sightseeing:
NPO Co. Ashoro Tourist Association　Kita 1-jo 1-chome, 1, Ashoro Town. Inside Michi no Eki Ashoro Ginga Hall 21 Tel: +81-156-25-6131

Feel dwarfed under the leaves... Ashoro's own astonishingly huge Rawanbuki plants

In Ashoro town's Rawan district, the Rawanbuki grows wild along the Rawan river. They reach heights of 3m, with a diameter of 10cm, making them Japan's biggest fuki plants. Registered as natural Hokkaido Heritage, they are strictly controlled and taking seedlings or seeds from Ashoro is forbidden, but there is one area of the Rawanbuki Hojo farm open to viewing by the public.

Harvest time is from early June to early July. When the massive stalks are cut water comes pouring out, and you can see how the water carries the blessing of growth.

Compared to regular fuki, these have less bitterness and are rich in minerals like calcium and magnesium. They're tender, with a pleasant taste and texture, and the local JA Ashoro sells processed products like Stewed Rawanbuki. Also, in late June you can try harvesting some yourself!

Rawanbuki is a variety of Akitabuki, but the reason for its enormous size is unknown. However, it is believed that factors like the climate, the volcanic soil, and the Rawan river's source Onneto lake, at the foot of Meakandake volcano, all play a part. Enormous fuki. Yet another gift of Mt. Meakandake.


◆How to get from Akanko Onsen to Onneto
Rental Car: Take National Highway 241 west about 6km, then turn left toward Obihiro. After 7.4km follow the sign and turn left, then go 6.6km ahead. (Closed in winter).
◆How to get from Akanko Onsen to Ashoro Town　
Rental Car: Take National Highway 241 west about 6km, then turn left toward Obihiro and go 48km ahead.

◆How to get to Rawanbuki Hojo
Take National Highway 241 west from Akanko Onsen about 6km, then turn left toward Obihiro. About 31km on, turn left onto Hokkaido Route 664. There's a sign about 13km ahead.

◆For information about Ashoro Sightseeing:
NPO Co. Ashoro Tourist Association　Kita 1-jo 1-chome, 1, Ashoro Town. Inside Michi no Eki Ashoro Ginga Hall 21 Tel: +81-156-25-6131