Yes you can swim in Cairns beaches, however it can be very dangerous between the months of November – May. Most locals would recommend swimming in freshwater lagoons, lakes and waterfalls to avoid crocodiles, jellyfish and other dangerous animals in the sea.

In Cairns and throughout Tropical North Queensland, the "unsafe" time for swimming in the ocean typically runs from November to May, which is known locally as Stinger Season. During these months, the warm coastal waters become the habitat for dangerous marine stingers, specifically the Box Jellyfish and the Irukandji. While you can technically still get in the water if you use a "stinger suit" (a full-body lycra suit) and stay within the protective stinger nets installed at major beaches like Palm Cove or Trinity Beach, most locals and safety experts advise against open-ocean swimming during this period. For those who want a worry-free experience, the Cairns Esplanade Lagoon is a massive, saltwater swimming pool that is safe year-round. Alternatively, the "best" and safest time to swim in the ocean is from June to October, when the water is cooler and free of jellyfish. It is also important to always be "Crocwise" in Cairns; regardless of the month, you should avoid swimming in murky water, near river mouths, or at night, as saltwater crocodiles are native to the region. Always look for the red and yellow flags and follow the instructions of the lifeguards to ensure a safe tropical holiday.