Alexandria Bay is located on the eastern side of the Noosa Heads National Park. It is by far Queensland's most popular free beach and has been used for nude swimming and sunbathing for many years. Most days there are quite a lot of people on the beach, sometimes hundreds on weekends. Unfortunately, in spite of many requests, it still does not have legal status.
There are a few different ways of getting in to Alexandria Bay. First of all you can drive down into the main part of Noosa Heads and turn right at the Hastings Street roundabout then follow the beach road around until it ends in the main National Park headquarters car park. It is then a very scenic 3 km walk into the beach and along to the southern end where the naturists tend to congregate.
Alternatively you can also enter the park from the southern end at Sunshine Beach, either via Solway Drive or Park Edge Road. You can also walk in from Sunshine Beach but it is quite a steep climb in places. The Solway Drive approach is the shortest but parking is very limited and strictly policed, so be wary