An exclusive economic zone (EEZ) is a point extending 200 nautical miles (370 km.) from a country's low water mark, which is a point on the shoreline that may not necessarily coincide with a low tide. In this zone, the proprietary country has exclusive rights to explore, exploit, and protect the assets of the sea within that area. The exclusive economic zone, for example, makes clear that a country can drill and sell oil, or the rights to oil, within that defined area. The zone is an extension of territorial waters and the contiguous zone.
To understand what an exclusive economic zone is, it is important to understand what other zones are extending into sea. The first boundary extending into sea is territorial water, which is the area in which all laws of a country or jurisdiction typically apply. This area extends 12 nautical miles (22.2 km.) into the ocean. The contiguous zone is an area in which a country may usually enforce laws such as customs and immigration. It extends 24 nautical miles (44.4 km.) into the ocean.
The contiguous zone is part of the exclusive economic zone, as are the territorial waters. After the exclusive economic zone are the high seas. This is an area in which no person can make a claim that is honored by any international agency. Some international laws may be enforced, but discoveries and resources can be claimed by anyone.
The Law of the Sea Convention in 1982 set up the current rule for the exclusive economic zone. Although established in the early 1980s, the convention did not go into effect until 1994. Since that time, the zones have been in effect for all coastal nations. In some cases, countries or jurisdictions without a coast may also have access to some EEZ areas.
Within an EEZ, the country or jurisdiction with rights has a great deal of control in how resources are used, despite what the wishes of the international community may be. For example, the United States could harvest fish species in its EEZ to a point that is considered unsustainable. No matter what the rest of the world thought, other countries would have no right to intervene. This is how some countries justify whaling.
In cases where there is less than 400 miles of ocean between the land of two countries, the EEZ may be limited to less than 200 miles each. In such circumstances, the countries usually split the difference evenly. So, for example, if there is 100 miles (161 km.) between two countries, they would each have 50 miles (approximately 80.5 km.) of EEZ.