We finally had that chance about a week or so ago when we were trying to find a water park to visit for the first time this summer, and also baby's first time swimming. So after some searching, I came across the Fuji Marine Pool (富士マリンプール).
Their facilities met all of our criteria: river pool, kids' pool, babies wearing swimming diapers OK. The place also has a neat little wave pool, several waterslides (some small speed slides and some tube slides), a concession stand/food shop, and lots of space to spread out towels and mats (which people do, so you'll want to get there early to find a decent spot, let alone in the shade). And Mt. Fuji in the background (not visible in the picture above though). Of course.
They also have a concession stand with various typical cheap food options (curry, yakisoba, ice cream, etc.).
We enjoyed spending our morning here with baby - definitely recommended!
