2026 Full-Day Course: Wanpaku Okoku Waterside Plaza

In the valley of Yamanakadani, Hannan City, near the border of Osaka and Wakayama, there is a free water play area called ‘Wanpaku Okoku Waterside Plaza’ (わんぱく王国 水辺の広場). In 2026 the season runs from Monday, June 1 through Monday, August 31, between 9:30 a.m. and 5:00 p.m. Since it's a shallow waterside area fed by water pumped from the nearby river, water may not be able to be released if the river's water level drops during extreme heat or similar conditions. There's a rule to check in at the management building's office before using the facility, so please stop by the management building first when you arrive. Admission is free, and parking is 500 yen for a standard car. There's a restroom in the management building. Being surrounded by mountains, the site has plenty of shade, and offering a coolness completely different from water play areas in urban areas is this spot's own particular appeal. In the morning, walk around JR Yamanakadani Station, taking in the remnants of the valley settlement that once thrived as a post town on the Kumano Kaido, and the greenery of the cherry trees lining the station. After that, get moving on the park's signature long roller slide, and in the afternoon, after lunch, head to the waterside plaza. It's a summery day of cooling off with the valley air and river water.