Nabegataki Park

Nabegataki Park is a scenic park centered around Nabegataki Falls in Kurobuchi, Oguni Town, Aso District, Kumamoto Prefecture. The centerpiece of the park, Nabegataki Falls, is a wide waterfall generally described as approximately 10 meters high and 20 meters wide. Some sources give its dimensions as approximately 9 meters high and 25 meters wide. It is known for its graceful appearance, with white water cascading like a thin curtain. The surrounding forest, sunlight filtering through the trees, spray, and moss-covered rocks combine to create a mystical landscape.

Nabegataki Falls became widely known after being used as a filming location for a television commercial for tea. Today, it is one of Oguni Town’s representative tourist attractions. Although it is not a particularly large waterfall in terms of height, its broad width and numerous streams of water flowing down in overlapping layers give it a delicate beauty quite different from that of a powerful, monumental waterfall.

The geological formations created by Aso’s volcanic activity are a defining feature of Nabegataki Falls. Approximately 90,000 years ago, a massive eruption associated with the formation of the Aso caldera occurred, sending high-temperature pyroclastic flows across a wide area of Kyushu. Volcanic ash, pumice, and rock fragments contained in the pyroclastic flows accumulated in thick layers while still extremely hot. These deposits were compressed and welded together by their own heat and weight, forming the geological foundation of the area around Nabegataki Falls.

Materials from Aso Geopark describe Nabegataki as a waterfall flowing over welded tuff. Welded tuff is a type of rock formed when high-temperature pyroclastic-flow deposits accumulate while retaining their heat, causing the particles to become compressed and welded together. At Nabegataki, relatively hard bedrock lies above a more easily eroded layer. As river water continued to flow over the area for a long period, the softer material below was gradually worn away, creating a large space behind the waterfall.

Even today, erosion progresses differently in the hard bedrock at the top of the waterfall and the softer material beneath it, so Nabegataki is gradually changing shape. As the lower layers are eroded, the hard bedrock above becomes overhanging and eventually collapses in places. Through the repeated processes of erosion and rockfall, waterfalls are generally thought to retreat upstream over long periods of time.

Nabegataki did not suddenly acquire its present form in the eruption of approximately 90,000 years ago. Rather, the eruption created the geological layers that formed the foundation of the waterfall, and the present landscape was shaped by the long-term erosion of the river that followed. Nabegataki is not only a place to enjoy beautiful scenery; it also offers an opportunity to observe firsthand the properties of pyroclastic-flow deposits and the erosive power of water.

Nabegataki’s greatest feature is the ability to walk behind the waterfall and view the falling water from the inside. Waterfalls of this kind are generally called “urami-no-taki,” or waterfalls viewed from behind. Behind Nabegataki is a large space carved out by erosion. The ASO Oguni Tourism Association describes this space as approximately 45 meters wide and 13 meters deep.

The view from behind the waterfall is completely different from the view from the front. A curtain of white water spreads out directly in front of you, while green trees and shafts of light can be seen shimmering beyond it. Depending on the volume of water and the position of the sun, sunlight filtering through the trees may stream through gaps in the falling water, while the spray sparkles in the light. Water sounds echo through the cave-like space beneath the rock, allowing visitors to feel the power of the waterfall not only through sight but also through sound and the cool air.

Viewed from the front, the beauty of the water flowing in a broad horizontal line is especially apparent. When the water flow is relatively gentle, numerous slender streams overlap, creating an appearance reminiscent of white lace or a translucent veil. After rain or during other periods of increased water flow, the waterfall becomes thicker and more powerful, presenting a more forceful landscape than usual.

However, immediately after rain or when the river is swollen, the current becomes faster and the ground more slippery. The park may be temporarily closed for safety reasons, and access to the area behind the waterfall or to the opposite bank may be restricted. Visitors should never approach the river recklessly during high water in pursuit of a more dramatic view.

Fine spray drifts through the area near the waterfall, and the air feels cool even in summer. Nabegataki is sometimes described as a refreshing place where visitors can experience “negative ions,” but rather than interpreting this as a claim of specific health benefits, it is more appropriate to think of the area as a place where the sound of water, cool air, and forest scents create a refreshing sensation. Spending quiet time while gazing at the waterfall allows visitors to forget the bustle of everyday life and enjoy a peaceful moment.

Nabegataki displays different expressions depending on the season and time of day. In spring, new leaves emerge and pale green foliage surrounds the waterfall. From early summer through summer, the forest becomes deeper green, creating a vivid contrast with the white water. The coolness provided by the spray and shade makes the waterfall a popular summer destination.

In autumn, the surrounding trees change color, and red and yellow leaves combine with the white water to create a beautiful scene. Fallen leaves decorate the rocks and surface of the water, enveloping the area in a calm atmosphere different from that of summer. In winter, light can more easily pass through the branches of trees that have lost their leaves, sometimes making the shape of the waterfall and surrounding geological layers clearer. However, roads and walking paths may freeze in the morning and evening during winter, so visitors should walk carefully.

Those wishing to photograph sunlight filtering through the trees should aim to visit on a clear day when sunlight shines onto the waterfall. However, the way the light enters varies depending on the season, weather, and time of day. The volume of water also changes considerably according to recent rainfall, so even when photographing from the same location, visitors can enjoy a different appearance each time they visit.

Nabegataki has previously hosted a limited-time spring illumination event called “Fantasy of Water and Light.” When illuminated, the waterfall takes on a fantastical appearance quite different from its daytime view, with the white water, surrounding rock surfaces, and mist enveloped in light. However, the illumination is not necessarily held every year on the same dates or with the same content. Visitors should check the official information provided that year by Oguni Town or the ASO Oguni Tourism Association for details regarding whether the event will be held, its dates and times, admission fees, entry procedures, and whether reservations are required.

The waterfall cannot be seen directly from the parking lot. It takes approximately three minutes on foot from the entrance of Nabegataki Park to the waterfall, but the route includes stairs and steep slopes. Although the walking paths are maintained, some areas may become slippery because of rain, spray, moss, or fallen leaves. Visitors are advised to wear comfortable, slip-resistant footwear such as sneakers or hiking shoes.

In particular, reaching the area behind the waterfall or crossing to the opposite bank may require walking over wet rocks and unstable ground. Oguni Town advises visitors entering riverside areas, including the area behind the waterfall and the opposite bank, to exercise great caution regarding falling rocks and falls and to act at their own risk. When the water level is high or access restrictions are in place, visitors must not enter the area behind the waterfall and should always follow the instructions of staff and on-site signs.

There is no wheelchair-accessible route from the entrance to the waterfall, and the stairs and steep slopes make it difficult to reach the area near the waterfall by wheelchair. Visitors with concerns about their physical strength or mobility, as well as those traveling with small children, should check the condition of the route and tour the area only within reasonable limits.

Nabegataki Park uses an advance reservation and online ticket-purchase system to reduce traffic congestion on surrounding roads and prevent overcrowding within the park. Online reservations can be made even on the day of the visit if spaces are available. However, on certain busy days during periods such as Golden Week and the Obon holidays, as designated in the official annual schedule, reservations are required for all visitors. Anyone without a reservation will not be admitted. Since the number of tickets is limited, visitors who have decided on a date are advised to reserve early.

For visitors unable to use the internet, the park also provides information about procedures that can be completed on the day at the ASO Oguni Tourism Association, provided spaces remain available. Reservations cannot be made by telephone. Since the reservation procedures and dates subject to mandatory reservations may change, visitors should be sure to check the official reservation website before traveling.

The regular opening hours are from 9:00 a.m. to 5:00 p.m., with final admission at 4:30 p.m. Admission is 300 yen for high school students and older, 150 yen for elementary and junior high school students, and free for children below elementary school age. The regular closing period is from December 28 through January 3 during the New Year holidays. However, the park may close temporarily because of heavy rain, flooding, typhoons, earthquakes, rising river levels, facility inspections, or other circumstances. Opening hours, admission fees, and usage conditions are subject to change.

The parking lot has space for 123 vehicles. Large buses cannot enter the parking area, and vehicle-size restrictions also apply to medium-sized buses and minibuses. Nabegataki Park is approximately 10 minutes by car or taxi from Michi-no-Eki Oguni Yu Station. It takes approximately one hour by car from the Hita Interchange on the Oita Expressway and approximately one hour and 30 minutes from the Kumamoto Interchange on the Kyushu Expressway.

Since public transportation options are limited, visitors traveling without a car should check bus schedules and taxi arrangements in advance. Nabegataki Park may not be displayed accurately in some car navigation systems. The official guidance therefore also suggests setting the nearby Sakamoto Zenzo Museum of Art as the destination and following the signs from there.

Nabegataki is one of the important sites that make up the Aso UNESCO Global Geopark. At a single location, visitors can observe the pyroclastic-flow deposits created by the massive eruption approximately 90,000 years ago, as well as the effects of long-term river erosion that followed. The unique landform that allows visitors to enter behind the waterfall clearly illustrates how layers of rock with different degrees of hardness have been gradually eroded by water.

Nabegataki Park is a place where visitors can experience beautiful water cascading like a curtain, a special view from behind the waterfall, the sound of water echoing through the forest, and the geology left behind by Aso’s massive eruption—all at once. While observing formations created by nature over immense spans of time, visitors can also learn about the geological origins of the Aso region.

Temporary closures and restrictions on access behind the waterfall may occur because of disasters, rising water levels, or other conditions. Before visiting, check the latest opening information on the official websites of Oguni Town and the ASO Oguni Tourism Association, along with the reservation status. By following safety instructions and taking care not to damage the natural environment, visitors can leisurely enjoy Nabegataki’s uniquely graceful and mystical scenery.