The coastline is famous for it's beautiful archipelago and white-painted wood towns, and is a favorite vacation area for Norwegians in the summer. It's pretty easy to travel between the coast towns. Outside the towns, however, public transport is rare.
The inland is far less visited and trafficked, but those interested in trekking to beautiful solitary lakes or whitewater activities - or mosquitoes - should give it a try.
Those interested in dialects, can observe the remarkable change up north along Setesdal, from the Danish-sounding Kristiansand dialect, to the very different north valley dialect that sounds more like Gaelic.
In Kristiansand you may get into trouble if you try real hard. If you travel by boat or in the winter mountains, make sure you know what you are doing. Otherwise, nothing of danger.