What is a narrow passage of water connecting two seas or two large areas of water called?

Answer: rivers

Explanation:

Rivers are one of the smallest form of "large" bodies of water when compared to all the other bodies of water like (oceans lakes ponds etc)

Answer:A strait is a narrow body of water that connects two larger bodies of water. It may be formed by a fracture in an isthmus, a narrow body of land that connects two bodies of water. Tectonic shifts can lead to straits like this.