Quote: The magnificent Bromo-Tengger-Semeru National Park (or Taman Negara in Indonesian) is a volcanic area with still a few active craters. The world heritage listed N.P. spans more than 50.000 ha and consists of a mountainous highland at least 1000m above sea level, making it cold during the night and chilly during the day, a welcome surprise after Indonesia's tropical climate. Highest mountain of the park and of the island is Gunung Semeru, a still active volcano. Almost every morning the volcano will blow some smokes. You can hike almost to the top of this mighty mountain, but it is supposed to be very difficult and it's far away from any passable road.

Easier to reach is the Tengger caldera on the north side of the park, probably formed after the collapse of an old volcano resembling the mighty Semeru. The caldera forms a depression in the highlands, with a width of almost 20km at places. The rocky rim rises almost 300m above the caldera floor. On the rim is the village of Cemoro Lawang. To reach this tiny village you will have to take a minibus or taxi from Probolinggo, 1.5 hours away at the foot of the mountains, and right on the Surabay to Bali road, at 4 hours from the Gilimanuk ferry to Bali. If you are staying in the north of Bali, the village of Cemoro Lawang can be reached in one day.
From journals The Most Populous Island in the World

Quote: To explore the Bromo area a little you would need at least one full day, so it's best to spend two nights in the village of Cemoro Lawang, on the rim of the Tengger caldera. A few cheap basic places are available to sleep (a few dollars a night will do). Most places will offer early morning jeep trips to the Penanjakan viewpoint. This is definitely a must, despite the unholy hour to get up (around 3am). It can be very cold, slightly above freezing temperature, so you will need a sweater or a jacket. The viewpoint is half an hour away, and when you arrive there will probably be some people already, waiting for the sun to rise.

When it gets clearer you will notice the fantastic landscape of the area, with amazing views on Gunung Semeru. Inside the caldera you will notice the perfect cone of Mount Batok, the ever-smoking Mount Bromo and the "sea" of black lava sand. The sunrays will set the area almost like on fire. Semeru will puff a few smokes as almost every day before turning to sleep again.

Most vehicles will leave for the village again and if you are leaving the same day it's better to go. We had the whole day so we decided to walk back to the village along the rim. As time went by Semeru got more and more cloudy and when we arrived in the village at lunch time, the mountain could not be seen anymore.

After lunch, we decided to explore inside the caldera, a steep climb down from the village. You can rent a horse to go down but we decided to walk down and across the black sand to Batok and Bromo. At the foot of Mount Batok you can see a Hindu temple. You can climb Bromo for a view and smell inside its smoking caldera. If you walk beyond Bromo you will notice that the caldera continues beyond another large mountain inside of it. And at this part of the caldera, the black sand has made place for grass and flowers. From here a path continues all the way to Mount Semeru, but be prepared for a long hike (2 to 3 days). We stayed in the caldera and returned the same way to the village when the path started to climb. It was evening when we returned to the village, exhausted but delighted by the wonderful landscape of this area.

This is definitely one of the most beautiful landscapes in the whole world!
From journals The Most Populous Island in the World