How to entertain my baby

I live in a small town where there is little to nothing to do. No mommy and me classes, barely any parks where other kids are out playing, not many places to walk around unless it’s in the woods and that’s sketch, so baby and I just stay at home and go for short walks throughout the day in our neighborhood. I’m struggling with different activities to do with him. He has a play pen he does a lot of playing in and I get in there with him half of the time, and then some Ms. Rachel, but that’s becoming more of a habit than I would like. He is 9 months old and an AVID crawler and a very active baby. I just got him a kiddie pool yesterday but we need something else to do during the day.