Wiktionary
navigation channel
n. (context nautical English) A deeper channel cut into the sea or river bed, to enable larger ships to pass through to a port.
Usage examples of "navigation channel".
Then we make a ninety-degree turn to port, enter the narrower portion of the navigation channel, which snakes into the old city past La Porte and Galena Park.
Although the navigation channel for oceangoing traffic in the lower reaches of the river averaged more than forty feet deep by one thousand feet wide, no ship the size of the United States had ever traveled on the Mississippi before.