Located about 6 miles away is Speelyi Beach Park on Lake Cle Elum. It's a great place to go to run around on the sand and take a dip in the lake. It's also pretty fun driving your car out on the sand. However, as my wife and I found out on a recent trip, there really isn't much of a beach until the end of summer when the water level goes down.
Check out how low the water is in this video shot on Labor Day 2013: