Travelled to Fitzroy island via Sunlover Reef cruise, basically a ferry service that lets you off at the island around 10 and picks you up at 4. Fitzroy is amazing. The beaches are covered in pieces of coral from the reef ranging from small to very large. However, you aren't allowed to collect it as the island is a national park and protected. There is a nice snorkeling beach right next to the pier. There is also a bar (Foxy's) where you can eat and get a drink. There is a hotel on the island too.
The island has various trails including the Nudie Beach trail and the Lighthouse Trail. Both are VERY strenuous. Nudie Beach trail is posted as a moderate hike but don't be fooled. It is very difficult and exhausting.
Fitzroy is a fun way to spend a day away from a lot of the commercialism of Cairns.