Far South East
A pleasant detour along the way would be along the historic Murray River, which used to transport goods on it paddle steamers. From here you can either continue north to Mildura before following the Calder Highway to Melbourne or the Balranald Highway to Canberra, or just return along your original coastal route.
Heading south from Adelaide you will get to Murray Bridge, which is the largest river town in South Australia. This town leads north into the other towns along the Murray River as well as south to the Dukes and Pacific Highway.
Once you hit the coast the first thing you will come across is the beautiful lagoon of the Coorong National Park heading all along the coast to Kinston SE.
Kingston SE is a large rock lobster fishing port and its fascination with lobsters is evident throughout the town. There is even a lively Lobsterfest held in January.
Slightly further south is another small fishing port called Robe, which is the one of the oldest settlements in South Australia. You can go swimming off of Long Beach and visit the museum in the Customs House to find out the history of the area. There are also the Chinamen's Wells which tell of a time when the government began charging tax per head on the Chinese gold miners. There are plenty of places to stay in Robe, as it is a very popular holiday destination.
Further south is another lobster fishing port of Beachport. The pretty port has good surfing and also offers windsurfing on Lake George and swimming in the Pool of Salmone. There are also a couple of museums that are worth visiting. Just before you reach Mt. Gambier you will come across Millicent near the beautiful Canunda National Park. Nearby are also the wonderful Tantanoola Caves.
The final place you will get to is Port Macdonnell, another lobster fishing port. There is a maritime museum where you can find out about the history of the area. There are also some great walks in the area around Mt Schank, as well as cave diving and snorkelling in Piccaninnie Ponds.
If you head along the Dukes Highway the last town that you will come across is Bordertown, a reasonably large town set amongst the beautiful country landscape that surrounds it. Although it takes longer from here you can head south to join the Princess Highway. On the way is Naracoorte, which is one of the oldest towns in the state, as well as Penola and the surrounding Coonawarra wine growing region.