While wearing a wetsuit is not strictly mandatory by law on the Great Barrier Reef in 2026, it is highly recommended by tour operators for two critical reasons: protection and buoyancy. During the winter months (June to August), the water temperature can drop to around 22°C (72°F), making a 3mm wetsuit essential for thermal comfort during long snorkeling sessions. In the summer months (November to May), "stinger suits" or thin lycra suits become necessary to protect against the potentially lethal Irukandji and Box Jellyfish that inhabit northern Australian waters. Beyond temperature and safety, wetsuits provide significant sun protection, preventing severe sunburn from the intense Australian UV rays reflecting off the water. Most tour boats provide these suits as part of the excursion fee or for a small rental price. If you choose not to wear one, you are significantly more exposed to coral scrapes, jellyfish stings, and the elements, so the vast majority of visitors opt for the suit to ensure their experience on the reef is both safe and comfortable.