Why do fish jump? Why don't lakes freeze all the way down to the bottom? Which lake plants are invasive? What are those water bugs? Is that lake healthy? Whether you fish, paddle, swim, snowshoe, ski, or just gaze upon your favorite lake, will deepen your appreciation for the forces that shape lakes and the teeming life in and around them. You'll discover the interconnected worlds of a lake: the water; the sand, gravel, rocks, and muck of the bottom; the surface of the lake; the air above; and the shoreline, a belt of land incredibly rich in flora and fauna. Explained, too, are the physical, biological, and chemical processes that determine how many and what kinds of fish live in the lake, which plants grow there, the color and clarity of the water, how ice forms in winter and melts in spring, and much more. Useful advice will help you look out for your lake and advocate for its protection.