Lakes are a very common occurrence to people around the world, except of course if you live in a dry remote area. These stagnant bodies of water are mainly the cause of glaciers from thousands of years ago. When the temperature of the planet was changing between ice ages and warm ages, glaciers ripped through mountains and landscapes carving large holes and valleys into the ground. Along with that, they deposited sedimentary rocks and other objects that can still be found today. These hollowed-out areas were then filled with water from melted glaciers, rain, and running water that is nearby. Some lakes are even human-made.
Within these lakes are isolated creatures, usually freshwater fish, turtles, mosquitos, and any other organism that needs stagnant freshwater in its lifecycle. One of the scariest things within these lakes are the parasites buried within. Things such as Giardia parasites cause stomach problems if consumed. This is why it is always important to know the water you are entering as well as make sure the water is clean before consuming or used for cooking. Even the larger animals can be dangerous. Things such as snapping turtles can have a bite strong enough to remove meat from your bone. Do not fear these messages, however, because people swim and live near lakes every single day.