By train
The Yeongdong line goes through Donghae, stopping at Donghae Station south of downtown and Mukho Station north of downtown. There aren't a lot of trains, however, and those there are don't go to too many places that are appealing to tourists, making the bus more convenient for most tourists.
By car
Highway 65 ends in Donghae and connects the city to Gangneung further north. From Seoul take highway 50 to Gangneung which then leads to the 65. South Korea uses a toll system for their inter-provincial highways. Seoul to Donghae costs W11,400 one way in tolls. However if you are a group of people at least 3 driving is a cheaper option than the bus. The trip from Seoul takes about 3 hours when there is no traffic.
By bus
For those using public transport, bus is the most convenient way to get to Donghae for most people. The bus terminal is a 20 minute walk north of the downtown area 5 minute cab ride. There are frequent buses to the Express Bus Terminal in Seoul takes a little over 3 hours, and less frequent buses to Dong Seoul East Seoul. There are also buses leaving every 10 minutes for Gangneung 35-40 minutes as well as buses to most other cities in Gangwon Province. There are 3 overnight buses to Busan.
By ship
Donghae serves as the main access point to Ulleungdo, 51,000 won each way with regular ferry service throughout the year usually once or twice a day in each direction, more frequent in the summer. Donghae also serves as the Korean stop in ferry service between Vladivostok, Russia and Sakaiminato, Japan (http://www.dbsferry.com/0...). Ferries leave from Mukho Port, a 5 minute drive north of downtown.