Where does a river typically flow into?

A river typically flows into its mouth, which is the point where it meets a larger body of water, such as an ocean, sea, or lake. At the mouth, the river often slows down and can deposit sediments it has carried along its journey, creating features like deltas in some cases. This area is crucial for various ecosystems and can also be significant for human activities such as fishing and shipping.

The other options refer to different components of a river system. A tributary is a smaller river or stream that feeds into a larger river, while the source is the starting point of a river, usually found in higher elevations. A watershed is the land area that drains into a particular river or lake, encompassing all the tributaries leading to it. All these terms describe parts of the river system but do not represent where the river ultimately flows into.