Kawah Ijen in East Java is known for its turquoise acidic crater lake, sulphur landscape and demanding pre-dawn climb.
Kawah Ijen is an active volcanic area in East Java, reached via a steep mountain trail from Paltuding. The official gate currently operates from 02:00 to 12:00 WIB, but access can change at short notice because of weather, volcanic activity or scheduled monthly closures.
Visitors must carry a health certificate issued no more than three days before the climb. Wear sturdy non-slip shoes, warm layers and a suitable mask, and follow all ranger instructions. Check the official conservation-area notice before travelling: closures and safety rules take priority over any itinerary.