Tyler State Park, in addition to being a stellar camping, hiking, mountain biking park also has a wonderful lake. People fish, canoe and swim in this lake which has a sand play area and a big floating dock that you can sun on, jump from, etc. Lots of fun. My husband and I use the lake for our open water swimming. From the sandy beach swim area to the pier directly across the lake is about 400 meters. The water is clean and fairly clear. There are no motorized boats allowed on the lake which is a huge plus for open water swimming. The park has a large changing and showering facility at the lake.
There is no life guard so you will be swimming at your own risk.