The volcanic island Jeju is the biggest island, relatively isolated from the mainland Korea. Jeju is well-knowned for 3 things: wind, stone and woman. You can find black basalt everywhere and the tradition of woman divers still continues: you can find 70 year old woman divers who are still working, catching sea animals. I've travelled Jeju only by cars, but my friends told me it's also great to travel around by bicycle or motorbikes. More easier way to discover local stuff.