Its a Strait (pronounced the same as straight) , a narrow channel of water that connects two larger bodies of water
strait
A narrow body of water connecting two larger bodies of water is called a Strait.
Straight
A strait is a narrow body of water that connects two larger bodies of water.
A strait is a narrow channel of the sea joining two larger bodies of waterAn Isthmus is a relatively narrow strip of land (with water on both sides) connecting two larger land massesOne is a thin bit of water between two big bits of land (that is a strait) whereas the other is a thin bit of land between two big bits of water (that is an isthmus).
A strait is a narrow body of water that connects two larger bodies of water. The opposite (a narrow piece of land that connects two larger pieces of land) is called an isthmus.
An isthmus is a narrow body of water between two lands.
A strait or, sometimes, narrows.
Strait
A narrow body of water connecting two larger bodies of water is called a Strait.
The term "marrow body of water" seems to be a miscommunication; perhaps you meant "narrow body of water." A narrow body of water between two larger seas is commonly referred to as a strait. An example of this is the Strait of Gibraltar, which separates the Atlantic Ocean from the Mediterranean Sea. Straits often serve as important navigation routes and can have significant ecological and geopolitical significance.
Canals; they have two lands and a narrow body of water in between!