Cairns is great, but it's a very small town. There are amazing rain forests that you can go on day trips through. It's also the best place to go snorkeling or scuba diving on the Great Barrier Reef.
It's a very touristy place, so you'll likely have many people approaching you trying to get you to go on their tours or pub crawls etc.
The beach in Cairns itself is very very crap. So crap that you're not allowed to swim there. There are jellyfish around and it's just very dangerous (and it looks all muddy). But there's a lagoon in the town center where everyone goes. It's great, get down there and take your bikini and sunscreen.
Have fun
