Oike Spring Group, a Hidden Power Spot at the Foot of Mount Kuro and a Forest of Famous Water

In the Asono district of Shonai-cho in Yufu, on the north side of Mount Kuro that rises at the eastern end of the Kuju mountain range, spreads the Oike Spring Group. Chosen among the Ministry of the Environment's hundred famous waters, it is a power spot rich in nature within the Aso-Kuju National Park.

Walking the boardwalk through old-growth forest from the parking area, you soon reach a pond of crystal-clear spring water. The water temperature stays around 12.6 degrees Celsius all year. The sight of mossy fallen logs and swaying water plants within the clear water feels as though you have wandered into another world.

Highlights

• Transparent spring water — About 14 tons of water well up each minute, roughly 20,000 tons a day, with clarity so high you can see right down to the bottom at your feet.
• Mossy old-growth forest — A forest lined with giant beech and maple trees, wrapped in a deep green that hardly feels like Kyushu.
• Hiking course — The trail leading from Oike to Kakushimizu and Sobabakke is a soothing route popular with nature lovers.

Enjoying the Seasons

In the fresh-green season the whole forest brims with life, and in summer the cool air of the springs brings relief. Autumn dyes the old-growth forest with red leaves and is the most popular season. Winter brings crisp air to the silent waterside. In every season, standing by the springs gives a refreshing sense of being washed clean.

Access and Basic Information

• Location: Asono, Shonai-cho, Yufu, Oita Prefecture
• Access: Hard to reach by public transport, so a car or taxi is essential. About 40 minutes via National Route 210 from the Yufuin interchange on the Oita Expressway.
• Entry (cleaning cooperation fee): 100 yen for junior high students and older
• Parking: Oike park parking available
• Facilities: Shop and restrooms available

Practical Travel Notes

• Recommended season and time of day: Autumn, when the leaves reach their peak, is the busiest. Early summer with its fresh greenery is beautiful too, and summer feels like a cool retreat thanks to the chilled spring air. Early morning, when the water surface is still and light filters in, is a good window with fewer people.
• Time needed: Just viewing the spring pond and walking back takes about 30 minutes to an hour. If you continue to Kakushimizu or Sobabakke, allow several hours round trip and come equipped as you would for a mountain hike.
• Nearby real spots: This is a trailhead for treks starting from Mount Kuro and Oike, and it is well loved by climbers of the Kuju range. Driving back toward Yufuin hot springs makes it easy to build a full-day plan combining bathing and meals.
• Budget sense: The cleaning cooperation fee is within a few hundred yen. Taking home spring water in a bottle is free, so there are no major costs.

A Quick Tip

Although there is a boardwalk, the path is left close to its natural state, so it is best to visit in easy-to-walk shoes. If you bring an empty bottle, you can take home some of the pure water fresh from the spring. The water stays cold even in midsummer, so it is also handy for keeping things cool. Take a deep breath before entering the forest and savor the clear air unique to an old-growth woodland with your whole body.

📚 Sources

For information on the Oike spring group, the main references are the tourism guidance published by Yufu City and the local tourism association, and the information on Aso-Kuju National Park and the 100 Famous Waters provided by the Ministry of the Environment. The spring-fed pond, the old-growth-forest path, and the hiking course leading to Kakushimizu and Sobabakke can be traced through such public guidance. The cleanup cooperation fee and facilities such as the shop and restrooms may change, so please confirm the latest details through official sources before you visit.

Visitor Checklist

• Estimated time: Just viewing the spring pond and returning takes about 30 minutes to 1 hour; if you go on to Kakushimizu or Sobabakke, allow a few hours round trip and equip yourself as for mountain hiking.
• What to bring: The footing is a natural path, so wear comfortable shoes, and carry coins for the cleanup fee (100 yen for junior-high age and up). Bring an empty bottle to take home spring water (cold even in midsummer). A shop and restrooms are available.
• Suggested route: From the Oike parking area, walk the old-growth-forest path to the spring pond; with time and gear to spare, continue to Kakushimizu and Sobabakke noted in the article, and on the way back combine with a bath tour or meal toward Yufuin Onsen.
• Crowd tips: Autumn foliage draws the biggest crowds, so the quiet early morning is best.