Several bus companies operate along the main road E18 / E39 between Oslo and Kristiansand / Stavanger.
Nor-Way Bussekspress: http://www.nor-way.no/nbeweb/show.do?page=150;1081
They all stop at Tangen by E18, where you can catch a local bus down to Kragerø. The connestion is quite OK, you usually will not have to wait very long at Tangen.
Should you have to wait, there is a shopping centre with a cafe and a chinese restaurant two minutes away from Tangen bus terminal.
You can travel to / between the islands by ferries or taxiboats. This picture shows the new, big ferry :-) A lot of people have their private boats, both tourists and residents, and it is possible to attend guided tours.
Phone nos for taxiboats:
908 84 888 - 992 70 506 - 971 73 147
905 80 405 - 941 50 740 - 922 95 366 - 928 86 699
There are two guest areas for boats downtown Kragerø, the Railway Quay and Barthebrygga. Mooring costs per night are:
- boats smaller than 30 feet: NOK 130
- from 31 to 40n feet: NOK 180
- larger than 40 feet: NOK 220
Below is the phone no of the harbour authorities:
Downtown Kragerø is small. When it comes to transportation, everything is within 5 minutes walking distance: Bus and taxi terminal, taxi boats and ferries. Jetties for mooring private boats are also close by.
Going by taxi is expensive in Norway compared to most other countries. A 5 minutes drive is appr. NOK 100, it is relatively cheaper the longer you go.
You can travel by train from Oslo or Stavanger / Kristiansand. You have to get off at Neslandsvatn, where the Kragerø line used to start. Nowadays there is a bus connection. Most of the buses pass Brøsjø, my railway station :-)