definition
strict definition
contiguous zone boundary
The limit of customs and immigration control at sea, twenty-four nautical miles from the baseline.
The contiguous zone reaches twenty-four nautical miles from the baseline, twelve beyond the territorial sea.
It is not sovereign territory. The country may enforce its customs, immigration, tax and sanitary law there and nothing further, so a vessel in the zone is outside the state while remaining subject to those four kinds of control.
The zone is set by the Convention on the Law of the Sea, article 33, and applies to countries rather than to regions inside them.