The Tama River in Ome isn't too deep, but it has enough current and rapids to be a popular spot for kayakers and rafters. And also fishermen, who by the way, fish with the very longest fishing poles I've ever seen! But anyway, we didn't go to fish or kayak, we just went to explore and throw rocks in the river, and it was a ton of fun.
There is a big pedestrian cable bridge near the area we entered from, so we crossed it to find a cute little outdoor cafe. We didn't end up eating there because they were closed by the time we were leaving, but next time we'll be sure to try them out! After crossing the bridge, we followed a path that went along the river until we found some steps leading down to its banks. The river is very rocky, and very shallow along the edges (don't know how deep the middle was, but I'm assuming not too deep), so it was perfect for little legs to splash around, explore, and throw rocks into the river over and over and over again!