The island is reached with a stunning 90 min journey along the coast, travelling through Tresteno and its arboretum, turning left at Ston and its castle and mussel beds. A quick lunch on the beach, mussels of course! Continuing on the peninsular you head towards Orebić.
Orebić is where you park and take the ferry to Korčula, if you go across as a pedestrian ( 10 Kunas, last time we were there ). Unless you plan to drive around the island or stay the night going over for an hour or 2 is great.
It is a wonderful old town, steeped in history. The bell tower of the church is worth a visit, for 3 Euros and good views from the top. There are lots of shops and restaurants and narrow streets to wander round.
Orebić itself is a small holiday resort and has a lovely promenade to stroll on with beach bars and restaurants. The sea around Orebić and Korčula has attracts higher strong winds and so here there is plenty of wind surfing and yachting.