Lake Okushima: Shima's Azure Jewel

Nestled in the Agatsuma District of Gunma Prefecture, Lake Okushima is an artificial lake created by the Shimagawa Dam in 1999. Despite its man-made origins, it has become a celebrated natural attraction, drawing visitors with its captivatingly blue waters. The lake's color, known as 'Shima Blue,' is most vivid from March to May when snowmelt flows into the lake, though it remains striking year-round. The lake's unique hue is attributed to the presence of allophane particles in the water, which scatter sunlight and create the vibrant blue effect. The color changes subtly depending on the season, sunlight, and time of day, offering a different visual experience with each visit. Visitors can explore the lake's surroundings via a 4-kilometer walking trail, enjoying panoramic views and the chance to encounter local wildlife like monkeys and wild birds. Water activities such as canoeing and stand-up paddleboarding are also popular, providing a unique perspective of the lake's clear waters and surrounding scenery. For those seeking a more relaxed experience, the nearby Cafe L'atelier Bleu offers refreshments and views of the lake. Lake Okushima is located within Joshinetsu Kogen National Park, offering access to other natural attractions in the area. The nearby Shima Onsen, a historic hot spring town, provides a perfect complement to a visit to the lake, offering opportunities for relaxation and cultural immersion.