The late 20th century saw a period of new definitions and disputes
regarding marine boundaries. Traditionally, each coastal state claimed
sovereignty over a territorial sea within a relatively short distance
of its coastline. Fishing disputes in the 1970's led some states to
claim a much larger marine territory. In 1982, the Third United Nations
Convention on the Law of the Sea (UNCLOS) set a number of territorial definitions
that have been broadly adopted. Full sovereignty is extended to a territorial
sea extending 12 nautical miles (about 19 kilometers) from the coast.
In addition, control over marine resources is extend to an Exclusive
Economic Zone (EEZ) extending 200 nautical miles (370 kilometers)
beyond the territorial sea of a nation's coastline (land at lowest tide).
Not surprisingly, this has led to a proliferation of disputes since
the EEZs of two or more states frequently overlap, especially where
states claim sovereignty to small islands. Since many nations, particularly
groups of islands, are in proximity it is common to have EEZs intersect
(see above map). There are three main types of EEZ boundaries.
Treaty boundaries have been formally recognized by neighboring
countries and are thus not contested. Median line boundaries have
mainly been established by the UNCLOS convention. While many have
been recognized by the concerned countries, a few are being
disputed. In some cases, disputed boundaries led to large areas of disputed EEZ, notably the
Spratly Islands on the South China Sea, portions being contested by
China, Vietnam, Malaysia and the Philippines. From a transportation
perspective, an important distinction is that vessels of other states
have the freedom of navigation within the EEZ. While they also
have the more restricted right to "innocent passage" through the territorial
sea, the coastal state has much greater authority over foreign vessels
in that zone.