It can be difficult to get my kids moving on weekends, but I knew just how to motivate them for an outing one Saturday. "Hey boys," I said. "Wanna go to a park where visitors fall into the water so often that they rent out spare clothes?"

I'd never seen my kids shed their pajamas so fast.

Within minutes we were out the door and on a train. Our destination? Shimizu Koen, a large park in Chiba Prefecture with a reputation for beautiful cherry blossoms. For kids, though, Shimizu Koen is better known for having the largest "field athletics" obstacle course in Japan.