Onjuku Town Waterpark (御宿町営ウォーターパーク)

Flow of the course

About this spot

A town-run outdoor pool in Onjuku, Isumi District, Chiba Prefecture -- 'Onjuku Town Waterpark' (御宿町営ウォーターパーク). In 2026 it's open from Saturday, July 18 to Monday, August 31. Despite being town-run, it boasts three types of water slides, and kids love comparing the different ways to slide and trying them again and again. The lazy river, where you drift along on a float, also makes for a pleasant rest spot for adults tired from swimming. There's a shallow kids' pool for little ones, so siblings of different ages can each enjoy their own way of playing. While Onjuku is known for its beach, a pool where you don't have to worry about waves is a reassuring option for families with young children. With a one-day pass, enjoy a summer-vacation-worthy day spent in the water until evening.

Season & hours

Tips

Fees, hours, and parking details vary by year, so be sure to check the official Onjuku Town website before you go. Water slides often have height or age restrictions, so if you're going with young children, check the conditions in advance for a smooth visit. Bringing your own float for the lazy river saves you from waiting. Shade is limited, so prepare rash guards and sunscreen, and take breaks often. Parking fills up quickly on summer weekends and during the Obon period.

Best time to visit

Entering at 12:30 gives you a full 4 hours until evening. After 3pm is a good time, when slide wait times get shorter.

Access & map

Onjuku Town Waterpark, Isumi District, Onjuku Town