Northeast Asian History Network

The Article 3 of Korea’s Constitution states, “The territory of the Republic of Korea includes the Korean peninsula and its adjacent islands.” Korea’s territory consists of the entire Korean peninsula, including North and South Korea. Korea shares borders with China and Russia in the north and is connected to the continent of Asia. The Korean peninsula is surrounded by the East Sea to the east, the Yellow Sea to the west, and the South Sea to the south.




There are more than 4,000 islands in Korea. In the East Sea are Ulleungdo and Dokdo, which mark Korea’s easternmost territory. In the South Sea are Jejudo and Marado, which mark Korea’s southernmost^{[note 003]} territory. In addition, there is an underwater island called Ieodo where a reef marine science base has been installed. In the Yellow Sea are Baengnyeong, Yeonpyeong, and other islands, as well.
All of these islands are within the sovereignty of the Republic of Korea.


The line that determines Korea’s territorial waters^{[note 004]}, also known as a maritime border, is important. The reason for this is that territorial waters are measured out to 12 nautical miles from the maritime border line.
The extent of a country’s territorial waters is determined using a normal base line and a straight base line based on the shape of the country’s coastline. The normal base line is a line that is revealed along a flat coast or on an isolated island in the sea at low tide. The straight base line refers to the line connecting the outermost island in the case of a coastline that is not flat and simple but wavy or complexly formed. The outermost island that is used to determine the maritime border is known as the base point island.


The coastlines along the Yellow Sea and the South Sea are complex and there are many islands close to the shore. Therefore, territorial waters are determined by a straight line of 12 nautical miles.
Territorial waters surrounding Jeju extend 12 nautical miles from the shoreline revealed at low tide.

Since the coastline along the East Sea is flat and simple, and there are no nearby islands, territorial waters are determined by the normal base line. Therefore, Korea’s territorial waters include the area 12 nautical miles out to sea as measured from the coastline seen at low tide.
Ulleungdo and Dokdo are both far away from Korea’s coast. In this case, territorial waters are measured based upon the location of these two islands. Therefore, 12 nautical miles of sea surrounding Dokdo and Ulleungdo is Korea’s maritime territory.

■ Let’s see and explain the reason for the difference between the extent of Korea’s ocean territory in the East Sea compared to that in the Yellow Sea and the South Sea.

Airspace is the sky above the land territory and the sea territory, and is very important in terms of airline traffic and national defense.
Sea territory, along with land territory, sets the standard for determining airspace. If sea territory is reduced, so is territorial airspace. Therefore, both maritime territory and land territory are important.

■ Let’s sit in on a class on Dokdo’s territorial rights at the Global History Diplomacy Academy.