A canal.
A narrow stripe of land that connects 2 large bodies of water is an isthmus.
A strait.
A strait is a narrow body of water that connects two larger bodies of water.
lakes
canal
A strait
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.
A canal.
Strait
A strait or, sometimes, narrows.
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 passage of water that connects two larger bodies of water, typically two seas or oceans. Examples include the Strait of Gibraltar and the Strait of Hormuz.