Overlapping territorial seas turn narrow waters into negotiated boundaries

What happens when two countries' twelve-mile territorial seas overlap?

They negotiate the boundary and practical arrangements, as Britain and France repeatedly do in the English Channel and around the Channel Islands.

Two twelve-nautical-mile territorial-sea claims cannot both extend without adjustment when the coasts are closer than twenty-four miles. The English Channel and Channel Islands provide practical examples of recurring Anglo-French boundary management. Governments exchange notes and negotiate working arrangements even when newspapers portray the latest disagreement as a dramatic rupture. Geography turns a simple legal distance into an enduring diplomatic task.