Donghae is a city in Gangwon Province, South Korea. There are two major ports: Donghae Harbor and Mukho Harbor. The city is located on the …Donghae is a city in Gangwon Province, South Korea. There are two major ports: Donghae Harbor and Mukho Harbor. The city is located on the Yeongdong Line railroad and the Donghae Expressway. Numerous caverns are found in the city, as in neighboring Samcheok. Hanzhong University was located here.