South Korea, officially the Republic of Korea (Korean: 대한민국), is a country in East Asia covering the southern region of the Korean Peninsula. To the north, South Korea borders North Korea, where the two were united as a country until 1948. The Yellow Sea is to the west, Japan is across the Sea of Japan, and the Korea Strait is to the southeast. The country is known as Hanguk (한국) by South Koreans, and Nam Chosŏn (남조선) by North Koreans. The capital of South Korea is Seoul (서울).
The area of South Korea is 100,339 km2, smaller than North Korea. The topography is mostly hilly and uneven. Mountains in the eastern region generally serve as the headwaters of large rivers, such as the Han River and Naktong River. Meanwhile, the western region is a low area consisting of muddy coastal land. In the western and southern regions where there are many bays, there are many good ports such as Incheon, Yeosu, Gimhae, and Busan.