Hanson Bay Wildlife Sanctuary is the go-to place to see koalas on Kangaroo Island and boy were there plenty to see when I visited. While we were advised that markers had been placed in front of five trees where they had been spotted by staff, we actually managed to spot many, many more as we explored the attraction.

The Visitors Centre and Cafe
The sanctuary itself was a bit of a let-down though, as it turned out to a be a lot smaller than I had expected (at least the part that you can access). There's just two short, but wide tracks, that are lined with mature trees.
However, while it looks a little disappointing, as I mentioned there were quite a few koalas in these trees. More trees are also being grown further back, surrounded by less-worn paths, and as these grow they will probably attract more koalas too and provide a larger area to explore.

One of the long wide paths you wander down
Despite the place feeling sort of like a zoo, the koalas at the sanctuary are wild and can come and go as they please (there are fences, but these are to keep other animals out). Apparently the sanctuary has 20 to 30 koalas who are often present, but the section you can walk through is only about 4% of the sanctuary's total space, so it sounds like the 15 or more I saw is unusual. You should always see a few here though, and orange flags are put out to help you spot them.

A sleeping koala

The koalas can be quite hard to spot - frustrating for some visitors, but fun for others
The sanctuary's priority is koalas but on my visit there were quite a few kangaroos roaming around too. They were particularly common in the open space near the car park (this area has a few tables for a picnic, but the Visitors Centre doesn't sell a huge variety of food, despite calling itself a cafe).

Other visitors find the best position to photograph the kangaroos
You can explore the sanctuary during daylight hours but you can also join a guided nocturnal tour. Start times for these vary, so you'll need to
click here to have a look at the latest schedule. These tours cost $24.00 for adults, $19.00 for visitors between 12 and 18, and $14.00 for children. Normal entry is $6.00 for adults and $3.00 for children under 12 years.
Hanson Bay Wildlife Sanctuary is not just about the animals; it also offers accommodation in the form of six beachfront cabins. These cost $170.00 per couple per night and can be rented for a minimum of two nights. More information can be found
here.
All of it is located on the western side of the island, with Kelly Hill Conservation Park (home of the
Kelly Hill Caves) on one side and
Flinders Chase National Park (where you'll find the
Remarkable Rocks,
Admirals Arch,
seals and more) on the other side. These are all worth seeing so staying in the area is worth considering, though there are plenty of other options.
Kingscote, the biggest town on the island, is an hour away from Hanson Bay Wildlife Sanctuary, and Penneshaw, where the ferry arrives, is a 90 minute drive too.