The wider Iceland-UK passage is closer to Britain, Norway, and the forward carrier fight, placing submarines amid more Allied bases and anti-submarine forces. A Soviet boat can instead travel north of Svalbard, follow Greenland's coast, and approach the narrower Greenland-Iceland section. That route is less crowded by the forces supporting Norway and the carrier groups. It also delivers Soviet boats directly toward the mid-Atlantic convoy zone while NATO attention is pulled east into the Norwegian Sea.
Notable Point · 2:25:19-2:29:22
Soviet submarines could favor the Greenland-Iceland route
A route north of Svalbard and down Greenland's coast avoids much of the Allied air and naval concentration east of Iceland.