Crystal Lake is a city located in McHenry County, Illinois, United States. It is a suburb of Chicago and has a population of approximately 40,000 people. The city is known for its natural beauty, with Crystal Lake being the largest natural lake in the state of Illinois. Crystal Lake offers a variety of recreational activities, including boating, fishing, and swimming. The city also has a vibrant downtown area with shops, restaurants, and entertainment options. Additionally, Crystal Lake is home to several parks, golf courses, and nature trails, making it a popular destination for outdoor enthusiasts.