Lake Onneto is a small, picturesque caldera lake nestled in the southwestern part of Akan National Park in Hokkaido. Known for its mesmerizing ability to change color depending on the season, weather, and viewing angle—from emerald green to deep blue and even turquoise—it's often referred to as the "Five-Color Lake." This natural phenomenon, coupled with the reflections of Mount Meakan and Mount Akan Fuji on its calm surface, makes it a significant natural attraction for those seeking untouched beauty.
Visitors consistently highlight the lake's tranquility and pristine natural environment as its main draw, contrasting it favorably with the more developed and tourist-heavy Lake Akan. Many reviewers emphasize the stunning reflections of the surrounding mountains and the vibrant autumn colors as particularly breathtaking. The peaceful atmosphere allows for quiet contemplation and excellent photography opportunities, especially on clear days. Some also mention the enjoyable hiking trails around the lake, including a path to a small, abandoned onsen, though its condition is noted as not well-maintained.
To make the most of your visit, aim for a clear day to fully appreciate the lake's color changes and reflections. Autumn is frequently cited as the best time due to the spectacular foliage, though early autumn can still be warm. Allocate about 30 minutes to an hour for a leisurely visit to the main observation deck, or longer if you plan to hike. Bring a good camera, and consider a drone for unique aerial shots, as suggested by some reviewers. Dress in layers, especially in autumn, as temperatures can be cool. There are restrooms available near the parking lot.
Lake Onneto is best accessed by car, as public transport options are limited. It's located about 25 minutes by car from Lake Akan. From Route 241, turn onto Route 949 (Onneto Line), which becomes a narrow road as you approach the lake. Reviewers advise driving slowly and carefully, especially as tour buses can also use this route. There are free parking lots available at the observation decks. Some visitors mention combining a trip here with a visit to Lake Kussharo or as a stop on the way to Obihiro.
A common complaint is that the lake's beauty can be diminished on rainy or cloudy days, with some visitors feeling it wasn't worth the drive under such conditions. To mitigate this, check the weather forecast before heading out. Another point raised is the narrowness of the access road; driving cautiously and being aware of oncoming traffic, including larger vehicles, is essential.