I've talked about some other sento being jungle gyms or theme parks with baths, but this one really takes the cake.
There is a large lukewarm pool outside with a slide for the kids. A water slide. For real. On top of that, the inside is decorated in a zoo animal motif. This is a super kid friendly sento. But, on the other hand, there are also unfriendly to children radon baths and saunas too. Overall, Sanko-yu is a fun sento and worth finding it under the Shinkansen tracks in Amagasaki. Many choices of baths and saunas and sitting places.

Unique and recommended. Perhaps my daughter's favorite sento.