Chatfield State Park is an awesome place to swim, hang out with friends and family, paddle board, kayak, and boat! My kids and I went this week and it was so much fun! I highly recommend Chatfield Swim area to get out of this Denver heat! Only $10 per car!
Here is some more info on all there is to do at Chatfield State Park! Enjoy!
https://cpw.state.co.us/placestogo/parks/chatfield