On February 10, 1897, a small refinery company called Mathilda sank the first oil drill into the earth near Balikpapan Bay. The date is now celebrated as the city's anniversary. Within a decade, the Dutch oil company Bataafsche Petroleum Maatschappij had established its headquarters here, building roads, wharves, warehouses, and bungalows for the engineers and managers imported from overseas. Multinational companies followed, drawn by reserves that would make Balikpapan the largest city in Kalimantan by GDP, with an estimated 73.18 trillion rupiah in economic output by 2016. The refinery that sits on the bay's shore today was founded in 1922 and still operates two subunits: Balikpapan I, which produces naphtha, kerosene, gasoline, and paraffin wax for domestic and international markets, and Balikpapan II, a hydro-cracking facility opened in 1983. Companies like Halliburton, Schlumberger, ChevronTexaco, and TotalEnergies still use the city as their base for operations across East Borneo.

Balikpapan's oil made it a target that empires could not ignore. On January 24, 1942, a Japanese invasion convoy arrived in the bay and was attacked by four U.S. Navy destroyers that sank four transports and a patrol boat. The Japanese landed anyway, meeting no resistance from Dutch troops who had been ordered to evacuate after destroying the oil installations. In retaliation for the sabotage, Japanese forces massacred 78 Dutch prisoners of war and civilians. Allied intelligence soon determined that half of all lubricating oil used by the Japanese military and sixty percent of its aviation fuel came from Balikpapan's refineries. The American 380th Bombardment Group attacked from Darwin, Australia, in August 1943, flying B-24 Liberators on a mission so long-range it seemed suicidal. The famous Shady Lady crash-landed but was repaired, and remarkably, no aircraft were lost. The 1945 Battle of Balikpapan concluded the Borneo campaign, but by then the refineries and seaport had been burned to the ground. Royal Dutch Shell completed major repairs only in 1950.

Thirteen years after World War II ended, Balikpapan was bombed again -- this time by its wartime ally. In 1958, the CIA was running a covert operation to undermine President Sukarno's government by arming right-wing rebels in the Indonesian archipelago. On April 28, a CIA pilot named William H. Beale flew a B-26 Invader painted black and bearing no markings over Balikpapan and dropped four 500-pound bombs. The first damaged the airport runway. The second set a British oil tanker ablaze and sank it. The third bounced off another tanker without detonating. The fourth struck the Indonesian Navy ship KRI Hang Tuah, killing 18 crew and wounding 28. Before the bombing run, Beale had also strafed the oil pipes running to Shell's wharf. The raid achieved its tactical goal: Shell suspended tanker services from Balikpapan and evacuated families to Singapore. The day before, Beale had attacked a Shell complex in Ambon. It was Cold War covert action at its most brazen -- an American pilot, in an unmarked plane, sinking allied ships in a friendly nation's harbor.

Balikpapan's official mascot is the sun bear, the smallest of the world's bear species and an animal endemic to Borneo's tropical forests. Only about 50 remain in the area around the city. Coal mining has narrowed their habitat so drastically that the bears have become reluctant to reproduce. They share their diminishing forest with proboscis monkeys, Bornean orangutans, gibbons, pangolins, and otter civets -- all classified as endangered. The Wain River Protection Forest, a 10,000-hectare reserve that serves as the city's primary water catchment, has lost roughly 37 percent of its healthy forest cover to encroachment, illegal logging, and fires. In 2009, a blaze consumed 15 hectares of both the Wain River and Manggar River forests. The reservoir within the forest is silting up from nearby coal mines and brick factories. Balikpapan was named Indonesia's Most Liveable City in 2013, but the tension between that title and the ecological damage required to sustain its economy grows harder to reconcile each year.

Balikpapan sits at a crossroads. Sultan Aji Muhammad Sulaiman Sepinggan International Airport serves 10 million passengers annually, equipped with 11 aerobridges and multi-level parking. The Port of Semayang connects the city by sea to Jakarta, Makassar, Surabaya, and beyond. The Balikpapan-Samarinda Toll Road, Borneo's first controlled-access expressway, opened in stages between 2020 and 2021 -- though it earned a reputation as Indonesia's loneliest toll road, its 9.9 trillion rupiah price tag criticized for low traffic volume. A 47-kilometer toll road connecting Balikpapan to Nusantara, Indonesia's planned new capital city, is under construction. That project may transform Balikpapan from a resource city into a gateway. The city's population, drawn from across the archipelago -- Javanese, Bugis, Banjar, Torajan, Madurese -- already reflects Indonesia's diversity. Whether Balikpapan can balance the pressures of new development with the ecological fragility that defines its landscape is the question that will shape its next century.