The city of Donghae was created in 1980 by consolidating the two small port towns of Mukho and Bukpyeong, as well as surrounding residential and industrial areas. It runs along the coast of the East Sea and includes the country's largest beach, Mangsang Beach, and serves as a major transportation port for the area. Though it's not the prettiest city, its best feature is that it's so close to the ocean.
The Donghae Station (tel. 033/521-7788) is located on the Yeongdong Rail Line and connects the city to Dongdaegu, Yeongju, Cheongnyangni, Busan, and Daejeon. Additional train service is added during the popular summer months from mid-July to August. Express buses run from Seoul's Gangnam express bus station 24 times a day (three additional buses on weekends) from 6:40am to midnight and take about 4 hours. From the Dong Seoul Station, buses run only about nine times a day from 7:50am to 7:30pm (one extra run on weekends, until 11:20pm) and also take 4 hours. Bus service is also available to and from Chuncheon, Wonju, Sokcho, Busan, Daegu, Taebaek, Gangneung, Samcheok, Ulsan, and Uljin. You can catch a ferry to Ulleung-do from here.
The tourist information center (tel. 033/533-3011; daily 9am-6pm) is just in front of the entrance to Cheon-gok Donggul.