The Adjacent Waters Boundaries (Northern Ireland) Order 2002 (SI 2002/791) is a statutory instrument of the United Kingdom government, defining the boundaries of internal waters, territorial sea, and British Fishing Limits adjacent to Northern Ireland.

The territorial waters defined come under the jurisdiction of Northern Ireland law, and are also used for defining the area of operation of the Northern Ireland Executive (including the Department of Agriculture, Environment and Rural Affairs) and other Northern Ireland Executive agencies and public bodies.

Because the order defines the territorial limits of the three separate jurisdictions, it comprises a piece of constitutional law in the constitution of the United Kingdom.

Northern Ireland waters is a colloquial term which can refer to different sea areas, including: The Order defines the maritime border with Ireland.

[3] The Order was referred to when Ireland made a claim for an area near Scandinavian countries' territorial waters.