What can run but never walks, has a mouth but never talks?

This flowing body of water, a constant traveler across landscapes, perfectly embodies the spirit of movement without ever taking a step. Its journey from a source, perhaps a mountain spring or glacial melt, sees it continuously "running" downhill, propelled by gravity. This ceaseless current, from a gentle trickle to a powerful torrent, gives the impression of tireless motion, yet it possesses no limbs to "walk" in the human sense.

Furthermore, this natural wonder possesses a distinct anatomical feature often found on maps and in geographical texts: a "mouth." This isn't an opening for speech or consumption, but rather the crucial point where the waterway empties into a larger body of water, such as an ocean, a lake, or another river. Despite this significant geographical "mouth," it remains eternally silent, incapable of producing sounds or engaging in conversation.

Rivers are far more than just answers to riddles; they are the lifelines of our planet. They have shaped civilizations, provided sustenance, and carved out the very valleys and canyons we admire. From the mighty Amazon to the smallest creek, each one plays a vital role in its ecosystem, transporting nutrients, supporting diverse wildlife, and offering a continuous, silent testament to the power and beauty of nature.