How the blockade cut Germany out of global trade

What was the effect of Germany's inability to convoy neutral trade during World War II?

It confined Germany largely to nearby trade such as Sweden while Britain continued drawing resources from a global maritime network.

The blockade was not absolute in every direction because Germany could still trade with Sweden. It nevertheless excluded the German economy from most global maritime networks. Britain retained access to resources from the Americas, Africa, Asia and Australasia through protected sea routes. The contrast shows that sea control mattered economically even when no single convoy battle decided the issue.