箱根河鸣园 Yunessun 一日通行证

We stayed here for hours with our four year-old. Great range of pools/rooms to explore - slides, bounce houses, playgrounds, caves, etc. The wristband payment system makes it easy to get food and drinks and other goodies while your stuff is stashed in lockers. The private onsen (nudity required) was also super relaxing, but we mostly went for the fun times in the family area.

We stayed at Hotel Ten-yu, which is connected via walkway to the Yunessun. We saw the advertisement for it at check-in and thought that we should check it out. We didn't expect to spend 2 hours there relaxing and experiencing all sorts of different springs.