The Bromo region is best-known for its awesome scenery; at its heart is a vast, ancient volcanic crater with sheer walls over 300m high. Within this crater, a host of picturesque mountains, including the dramatic, still-smoking Gunung Bromo (2392m), rises up from the "Sea of Sand", the sandy plain at the crater's base. Hundreds of thousands of visitors come here each year to climb Bromo for the sunrise - a stunning sight, and less strenuous than many other Indonesian peaks.

One hypothesis for the formation of the area is that Gunung Tengger, then the highest mountain in Java at over 4000m, erupted to form a caldera of between 8km and 10km in diameter and crater walls between 200m and 700m high. This is now the main outer crater rim with the Sea of Sand in the bottom. However, eruptions continued to occur, forming the smaller inner peaks such as Bromo, Batok and Widodoren that rise up from the Sea of Sand.

This unique landscape now comprises the Bromo-Tengger-Semeru National Park, whose highlights are the dramatic smoking crater of Gunung Bromo, Gunung Penanjakan , on the outside crater's edge and one of the favourite sunrise spots, and Cemoro Lawang , with its brilliant panoramic view of the crater, where most visitors stay. The park also contains the highest mountain in Java, Gunung Semeru , which can be climbed by experienced trekkers. Views are best in the dry season but, whatever time of year, you should bring warm clothes.

There are two main approaches to the Bromo region. The most popular is to head inland from Probolinggo , on the north coast, to the crater's edge at Cemoro Lawang, where most people stay in order to make the dawn trip to Gunung Bromo as easy as possible. Alternative access is from Pasuruan , also on the north coast, inland to the villages of Tosari and Wonokitri. These villages are linked by road to Gunung Penanjakan, so they offer an excellent approach for the sunrise from there.