Lakes are large bodies of water surrounded by dry land. They may have rivers, streams or waterfalls flowing into them or out of them. They may contain islands or artificial structures within their perimeter. Lakes may vary in depth from shallow to incredibly deep and may hold underwater elements such as ruins, shipwrecks, and underwater caves beneath their surface. They may have docks, fishing towns, or summer camps on their shores. In fictional worlds lakes may be sites of legend, a home to cryptids or leviathans, or contain water with magical properties. They may have regions within them that contain tall reeds or giant water lilies.
Consider how the characteristics of the lake can impact or enhance your region or world’s tone. A cold, deep lake, mirky water full of grasping plants, and a mist settled on the surface are elements that can be used to create unease or mystery.
When designing lakes, consider the general region in which they are located as well as their characteristics such as size, shape, and depth. Lakes may be a single, vast body of water, or may be a winding series of interconnected spaces. Lakes may be fed by rainfall, rivers & streams, or springs. Consider both the inflow and outflow points of the lake. Lakes may be fed by multiple inflowing sources, but it is exceptionally rare that they have more than one naturally occurring outflowing river or stream.
If you are struggling with the topology of your fictional lake, use existing real world lakes as a reference or starting point.
Consider the local terrain in which the lake exists. Are there mountains surrounding it or forests? Is this lake nestled in a canyon? The local terrain will determine what the coast of this lake may be like, such as whether it has sandy beaches or coastal cliffs.