It took half an hour from Tong Yeong city by ship. It costs 10,000 won per person(Based on Dec 2010) for a round-trip ticket. Hansan Island is known for a historic place that Admiral Yi Sun-sin protected korean from japanese invaders in 1952. Now visitors are allowed to enter and walk around there. I highly recommend one of the remarkable attractions in Korea.
Tong Yeong City Website : http://eng.tongyeong.go.kr/main/default.asp