Mount Bromo sits in the middle of a vast plain called the "Sea of Sand" a protected nature reserve since 1919. The typical way to visit Mount Bromo is from the nearby mountain village of Cemoro Lawang. From there it is possible to walk to the volcano in about 45 minutes, but it is also possible to take an organised jeep tour, which includes a stop at the viewpoint on Mount Penanjakan (2,770 m or 9,088 ft). The best views from Mount Bromo to the Sand Sea below and the surrounding volcanoes are at sunrise. The viewpoint on Mount Penanjakan can also be reached on foot in about two hours. From inside the caldera, sulfur is collected by workers.
Depending on the degree of volcanic activity, the Indonesian Centre for Vulcanology and Disaster Hazard Mitigation sometimes issues warnings against visiting Mount Bromo.
On the fourteenth day of the Hindu festival of Yadnya Kasada, the Tenggerese people of Probolinggo, East Java, travel up the mountain in order to make offerings of fruit, rice, vegetables, flowers and sacrifices of livestock to the mountain gods by throwing them into the caldera of the volcano. The origin of the ritual lies in the 15th century legend where a princess named Roro Anteng started the principality of Tengger with her husband, Joko Seger. The couple were childless and therefore beseeched the assistance of the mountain gods. The gods granted them 24 children but stipulated that the 25th child, named Kesuma, must be thrown into the volcano as a human sacrifice. The gods' request was implemented. The tradition of throwing sacrifices into the volcano to appease these ancient deities continues today and is called the Yadnya Kasada ceremony. Though fraught with danger, some locals risk climbing down into the crater in an attempt to recollect the sacrificed goods that they believe could bring them good luck.
On the Segara Wedi sand plain sits a Hindu temple called Pura Luhur Poten. The temple holds a significant importance to the Tenggerese scattered across the mountain villages, such as Ngadisari, Wonokitri, Ngadas, Argosari, Ranu Prani, Ledok Ombo and Wonokerso. The temple organises the annual Yadnya Kasada ceremony which lasts for about one month. On the 14th day, the Tenggerese congregate at Pura Luhur Poten to ask for blessings from Ida Sang Hyang Widi Wasa and the God of Mahameru (Mount Semeru). Then the crowd proceeds along the crater edges of Mt Bromo where offerings are thrown into the crater. The major difference between this temple and Balinese ones are the type of stones and building materials. Pura Luhur Poten uses natural black stones from volcanoes nearby, while Balinese temples are mostly made from red bricks. Inside this pura, there are several buildings and enclosures aligned in a mandala zone composition.
Mount Bromo erupted in 2004. That eruptive episode led to the death of two people.
On Tuesday, 23 November 2010, 16.30 WIB (Western Indonesian Time), the Indonesian Centre of Vulcanology and Geology Hazard Mitigation (CVGHM) confirmed the activity status of Mount Bromo at "alert" due to increasing tremor activity and shallow volcanic earthquakes at the mountain. Concerns were raised that a volcanic eruption might be likely to occur. As a precaution local residents and tourists were instructed to remain clear of an area within a radius of three kilometres from the caldera and refugee encampments were erected. The area surrounding the Teggera caldera of Bromo remained off-limits for visitors throughout the remaining part of 2010.
Bromo started to erupt ash on Friday 26 November 2010.
On 29 November 2010 Transport Ministry spokesman Bambang Ervan announced that Malang's domestic airport would be closed until 4 December 2010. Malang is a city of about 800,000 people is about 25 km (16 mi) west of Mount Bromo. Abdul Rachman Saleh Airport normally handles 10 daily domestic flights from the capital Jakarta. Government volcanologist Surono reported that the volcano was spitting columns of ash some 700 metres (2,300 feet) into the sky.
On 23 January 2011 an exclusion zone was recommended for communities living around Mount Bromo. Tourists and hikers were to advised not to come within a radius of 2 km from the active crater. CVGHM stated that they expected warning signs to be installed stating the limit radius of 2 km from the crater. Operational caution was recommended for flights into and leaving Juanda International Airport IATA:SUB in Surabaya. CVGHM recommended the establishment of public areas for the provision of face masks and eye protection. CVGHM also issued a warning to residents to be cautious of ash build up on roofs and other places that may give cause for collapse under the burden of ash.
Further eruptions and the issuing of Aviation Ash advisories on 27 January and 28 January 2011 led to concerns being raised regarding a volcanic ash plume, reported to be drifting eastward toward the air corridors used to access the Ngurah Rai International Airport IATA:DPS in Bali. Airport official Sherly Yunita was reported at the time as stating that concerns about visibility had prompted Singapore Airlines, Jetstar-ValueAir, Air France-KLM, Virgin Blue and Cathay Pacific to cancel several flights to Bali, 340 km (210 mi) to the east. SilkAir also cancelled flights on the 27 January between Singapore and Lombok, an island to the east of Bali. he Volcanic Ash Advisory Centre in Darwin, Australia released several Code Red Aviation Ash Advisories pertaining to Mount Bromo (Tengger Caldera), on 27 January. They indicated that ash was observed at altitudes up to 18,000 ft (FL180) extending 200 nautical mi to the south east of the caldera. In other ash advisories of that day the cloud was reported as at times having a 10 km/h drift, both to the east, and to the south east.
Deformation-late November 2010-late January 2011
The Indonesian Centre for Volcanology and Geological Hazard Mitigation (CVGHM) reported on 13 January 2011, that deformation using tiltmeter measurements indicated an inflation at rate of 5 micro radians between 25 November 2010 and 14 December 2010 and a relatively stable since 15 December 2010 both on Radial Components and Tangential Components.
Deformation measurement using electronic distance measurement equipment compared observations at designated measuring points; POS-BRO, POS-KUR and POS-BAT during the period 25 November 2010 - 20 December 2010 with observations from the period 21 December 2010 - 30 December 2010 indicated the shortening of the distance from the POS-BAT, or inflation. Observations between 30 December 2010 to 23 January 2011 were reported as relatively stable.