A strait
A strait is a narrow channel of water that connects two large bodies of water. A gulf is a large bay that is an arm of an ocean or sea.
A Strait, such as the Bering Strait between Alaska and Russia or the Strait of Gibraltar between Europe and Africa.
Normally, that would be a Strait.
No that would be a tributary
A narrow channel joining two larger bodies of water
strait
A narrow body of water connecting two larger bodies of water is called a Strait.
A narrow body of water that connects two larger bodies of water (oceans?) is a strait. Examples are the Strait of Gibraltar, Malacca Strait, Yucatan Strait, Strait of Dover, and so on.
A strait is a narrow channel connecting two bodies of water.
A comparatively narrow passageway connecting two large bodies of water.
what is an articial waterway