UNCLOS fixes a 12 nautical mile territorial sea and a 200 nautical mile exclusive economic zone
Background
Hook: the IMO reported three hijacked ships freed off Somalia, at sea where UNCLOS sets the legal zones. The UN Convention on the Law of the Sea was opened for signature on 10 December 1982 in Montego Bay, Jamaica and entered into force on 16 November 1994. Coastal States exercise sovereignty over a territorial sea whose breadth does not exceed 12 nautical miles. They have sovereign rights in a 200-nautical mile exclusive economic zone (EEZ). The Convention also established the International Tribunal for the Law of the Sea.
Territorial sea:
up to 12 nautical miles
Exclusive economic zone:
200 nautical miles
Opened for signature:
10 December 1982, Montego Bay
Why it matters for exams: Maritime zones and the sovereignty versus sovereign-rights distinction are regular UPSC and PSC points.
Kerala PSCUPSC
In plain words
EEZ Exclusive Economic Zone — A zone up to 200 nautical miles where the coastal State has sovereign rights.