More than 100 species of jellyfish have been recorded along the Great Barrier Reef, including the notorious stinging blue bottles and box jellyfish. One of these, the infamous Irukandji jellyfish, is one of the smallest (roughly one cubic centimetre) and most venomous jellyfish in the world.

Yes, box jellyfish (specifically the Chironex fleckeri and the smaller, elusive Irukandji) are present in the waters of the Great Barrier Reef, but their presence is highly seasonal and regional. They are most common during "stinger season," which typically runs from November to May in North Queensland. During this time, the risk is highest in the shallow coastal waters and near the mainland beaches rather than on the outer reef itself. Because box jellyfish are not strong swimmers and prefer the calm waters of the coast and estuaries, the outer reef platforms (where most snorkeling tours go) are generally considered much safer. However, because Irukandji jellyfish can occasionally be swept out to the reef by currents, most reputable tour operators provide "stinger suits"—full-body lycra or neoprene suits—to all guests. These suits not only provide nearly 100% protection against jellyfish stings but also offer excellent sun protection. While a sting from a box jellyfish can be life-threatening, the risk to the average tourist is very low as long as they follow local advice and wear the provided protective gear during the designated stinger months.