Ijen Crater Nature Tourist Park
The Ijen Plateau features three different volcanoes - Ijen, Raung & Merapi. This is one of the most seismically active areas of Indonesia, and the names of the three volcanoes bear this out. While Lonely Mountain for Ijen sounds relatively benign, 'to roar loudly' (Raung) and 'mountain of fire' (Merapi) tell the truer story. The real drawcard here is the Ijen volcano, which has a one kilometre wide, turquoise coloured, acidic crater lake. The lake is the site of a labour-intensive sulphur mining operation, in which sulphur-laden baskets are carried by hand from the crater floor - you'll pass collectors who work around the tourists on the trail. The pungent sulphur at the bottom of the crater is toxic though, and can be overwhelming for some - therefore, visits should probably be quick to avoid your lungs or eyes getting too affected. Vistas of the lake from the peak of Gunung Ijen are spectacular, and highly recommended at sunrise if you can make it early enough.