a rapid
Kyle means "narrow, straight".
a strait is a narrow passage (found in my social studies book)
Canal
The water that flows in streams and rivers into the ocean and lakes is called runoff or freshwater.
It could be a spring or artesian well, from which water flows. Or a well in which water seeps rather than flows.
The Dardanells.
a straight
Isthumus
a strait
The Strait of Gibraltar.
If you are talking about a piece of narrow land that sticks out into a body of water, then it is called a peninsula.
A river.