The smallest body of water is typically considered to be a puddle. A puddle forms when rainwater or other liquids collect in a small, low-lying area of land. Unlike larger bodies of water such as lakes, rivers, or oceans, puddles are temporary and can evaporate or soak into the ground relatively quickly.
Puddles can vary greatly in size, but they are generally small enough to not have a significant impact on the surrounding environment. They can be found in urban areas after rainfall or near plants and trees in natural settings. In some scientific contexts, terms like ‘micro-pool’ or ‘micro-habitat’ might refer to extremely small water collections which host specific organisms, but generally, a puddle serves as a straightforward example of a small body of water.