The line runs from Greenland through Iceland to the United Kingdom and mattered because it lay across Soviet access to the North Atlantic. Its width makes it unlike a conventional geographic choke point: battle groups can manoeuvre there for days without seeing land. Controlling it depends on layered surveillance, air power, submarines, and sea control rather than fixed fortifications. The gap is a defended strategic transit route whose effectiveness rises or falls with the forces assigned to watch it.
Chapter · 36:14-38:12
Why the GIUK Gap is a strategic transit route
The Greenland-Iceland-United Kingdom gap is a vast defended transit route, not a narrow strait that a few ships can simply close.