Wonsan (Korean pronunciation: [wʌn.san]), previously known as Wonsanjin (元山津), is a port city and naval base located in Kangwon Province, North Korea, along the eastern side of the Korean Peninsula, on the Sea of Japan and the provincial capital. The port was opened by Japanese forces in 1880.

Before the 1950–1953 Korean War, it fell within the jurisdiction of the then South Hamgyong province, and during the war, it was the location of the Blockade of Wonsan. The population of the city was estimated at 329,207 in 2013. Notable people from Wonsan include Kim Ki-nam, a diplomat and former Vice Chairman of the ruling Workers' Party of Korea.

In 2013, it was announced that Wonsan would be converted into a summer destination with resorts and entertainment. Having spent his childhood years there, Kim Jong Un has expressed significant interest in developing the region, with the construction of new infrastructure such as Kalma Airport, a dual-use civilian international airport and military proving ground. A state corporation, the Wonsan Zone Development Corporation, has been established with feasibility studies for a wide variety of hotels and commercial and industrial development.

Wonsan has also been known as Yonghunghang, Yuanshan in Chinese, Genzan or Gensan in Japanese, and Port Lazareva or Port Lazarev in Russian.

Wonsan's area is 269 square kilometres (104 sq mi). It is located in Kangwon Province, on the westernmost part of the Sea of Japan and the east end of the Korean peninsula's neck. Mt. Changdok (Changdok-san) and Mt. Nap'al (Nap'al-san) are located to the west of the city. More than 20 small islands flank Wonsan's immediate coastal area, including Hwangt'o Island and Ryo Island. Wonsan is considered an excellent natural port location. Mount Kŭmgang is located near Wonsan.

Wonsan serves as the administrative center of Kangwon Province.

The City of Wonsan (Wonsan-si) is divided into 45 tong (neighborhoods) and 14 ri (villages):

The city has a humid continental climate (Köppen Dwa).