Cairns, like much of Australia, is a very safe city with very little crime occurring amongst locals and tourists. Take the usual precautions of being vigilant with personal belongings, especially around clubs and bars late at night.
There are no mandatory vaccinations required for entry into Australia, but make sure you have a strong insect repellent to fend off mosquitoes and pesky insects.
If you are planning any off-road adventures, it is best to plan your trip well and have a reputable knowledge of the wilderness, or join a tour group as road conditions may not be optimal due to flooding over the wet season. Keep in mind that rental agencies have certain limitations regarding where the vehicle may be driven, so please check ahead of time.
When swimming at the beach, be aware of marine stingers (or jellyfish). You should only swim in designated swimming areas during the months of May to November when these animals are rife. Lycra wetsuits can be rented at the beach for extra protection. Be mindful of crocodiles and snakes when out in swampy areas and hiking trails. Pay attention to the signboards and remember that these animals have right of way.
Should you need emergency assistance, dial 000 from any landline.