Methanol poisoning
Locally produced arak and counterfeit branded spirits have repeatedly been found contaminated with methanol, causing deaths and permanent blindness among tourists. Symptoms — vision changes, severe headache, vomiting — can appear 12 to 24 hours after drinking.
Stick to beer, wine and sealed bottles from reputable outlets, avoid free spirit-based cocktails and arak entirely, and seek hospital care immediately if vision is affected.
Volcanoes and the sea
Indonesia has around 130 active volcanoes; eruptions close airports several times a year. Check alert levels before booking treks.
Rip currents on Bali's south and west coasts drown swimmers regularly. Swim between the flags at patrolled beaches such as Kuta and Legian.