2026 Iriarai Nishi Park Water Play Area: A Full One-Day Course

Iriarai Nishi Park (入新井西公園) in Ota City has a free water-recreation facility with a waterfall, a pond, and a stream, the Iriarai Nishi Park Water Play Area. In 2026 it is scheduled to open from Fri, May 1 until around Wed, September 30, from 10:00 to 16:00. The closing date is not announced on the city official site, so late September is the usual guide. It is closed on the regular cleaning days of August 10 and August 25, so plan around those dates. The water is filtered and disinfected, but it is not drinkable. The site is Iriarai Nishi Park in Ota City, in a townscape within walking distance of JR Omori Station (大森駅). Admission is free. In the morning, visit the Omori Nori Museum, where displays of actual tools and fishing boats show that the sea off Omori was once one of Japan's leading nori seaweed production areas. Move straight next door to Omori Furusato-no-Hamabe Park (Omori Hometown Beach Park) and have lunch in the sea breeze on the first artificial sandy beach developed in the ward. In the afternoon, enjoy the water at the Iriarai Nishi Park Water Play Area until it closes at 16:00. Because you trace memories of the sea before getting into the water, the very same water looks different. It opens in May, so another welcome point is being able to set out from the pleasant days of early summer.