Borneo is the world’s third largest island after Greenland and New Guinea, shared by Indonesia in the south and center (Kalimantan provinces), Malaysia in the north (states of Sabah and Sarawak), and the Sultanate of Brunei on the north coast. Its name likely traces to Brunei, an early polity on the island’s coast, while Indonesians call the island Kalimantan. Population is roughly 23 million across all jurisdictions, speaking Malay and Indonesian as lingua francas alongside dozens of indigenous Dayak, Dusun-Kadazan, Iban and other languages, plus Chinese varieties and widespread English in Malaysian Borneo and Brunei. Political status is split: Brunei is an absolute monarchy under Sultan Hassanal Bolkiah; Sabah and Sarawak are Malaysian states with special autonomy within a federal constitutional monarchy; Kalimantan is governed by Indonesia’s presidential republic. Gambling is illegal in Brunei and Indonesia and tightly restricted in Malaysian Borneo; lotteries exist but Muslims are prohibited from participation. Defense is handled by each state’s armed forces: Indonesia’s TNI in Kalimantan, the Malaysian Armed Forces and ESSCOM security zone in eastern Sabah, and the Royal Brunei Armed Forces; the British Army maintains a Gurkha presence and jungle training in Brunei. Major cities include Kuching, Kota Kinabalu, Bandar Seri Begawan, Samarinda, Balikpapan, Pontianak and Banjarmasin.

History
Borneo’s human story begins with Paleolithic cave dwellers whose hand stencils and burials animate sites like Niah and Mulu in today’s Sarawak. For millennia coastal trade knit the island into Austronesian and later Indian Ocean networks, bringing Hindu-Buddhist influences and then Islam by the 14th-15th centuries through sultanates such as Brunei and Sulu. In the 16th century Iberian voyages reached the archipelago, but it was the 19th century that reshaped the map: British adventurer James Brooke became the White Rajah of Sarawak in 1841, founding a dynasty that expanded its territory through treaties and campaigns against piracy and headhunting, while the British North Borneo Company administered what became Sabah. The Dutch consolidated control over southern and eastern Borneo as part of the Netherlands East Indies, codifying the term Kalimantan for their domains.
World War II brought Japanese occupation across the island, forced labor, and the tragic Sandakan Death Marches in Sabah. Allied operations and local resistance eventually forced a Japanese surrender in 1945, after which decolonization accelerated. Dutch Borneo joined the new Republic of Indonesia in 1949 as Kalimantan. In 1963, Sabah and Sarawak joined the Federation of Malaysia while Brunei declined to join after the 1962 revolt and remained a British protectorate, gaining full independence in 1984.
The 1963-66 Indonesia-Malaysia Confrontation saw cross-border incursions in the jungles of Borneo as Indonesia opposed the formation of Malaysia; British, Australian, New Zealand and Malaysian forces conducted counterinsurgency along the border with Sarawak and Sabah. In parallel, Sarawak and Sabah experienced communist insurgencies of varying intensity into the 1980s, while Brunei remained relatively stable under the Sultan. Since the late 20th century, logging and the expansion of palm oil transformed large areas of lowland forest, prompting conservation efforts and the designation of national parks such as Gunung Mulu and Kinabalu. The 21st century has focused on balancing development with biodiversity, upgrading trans-Borneo highways, and cross-border initiatives like the Heart of Borneo conservation program connecting Brunei, Sabah, Sarawak and Kalimantan. Tourism has grown around diving at Sipadan, wildlife corridors in Sabah and Sarawak, and river and forest tourism in Kalimantan, even as communities negotiate the legacies of migration, land rights, and cultural revival of longhouse traditions.

Industry
Borneo’s economy pivots on oil and gas, timber, palm oil, mining and growing services. Brunei’s economy is dominated by hydrocarbons with LNG exports from Lumut and onshore oil at Seria. Malaysian Borneo hosts refineries, shipyards, and petrochemical and LNG facilities in Bintulu, while Kota Kinabalu, Kuching and Miri anchor services and regional tech and logistics. Indonesian Kalimantan produces coal in East Kalimantan, bauxite in West Kalimantan, gold and timber products, alongside palm oil milling and downstream oleochemicals. Global brands are not headquartered here, but many consumer goods are manufactured or assembled regionally, and oil majors and service companies operate extensively. Industrial records include the Sarawak Corridor of Renewable Energy’s hydropower-supported aluminum smelting and one of the world’s largest LNG complexes at Bintulu.

Flora and fauna
Borneo’s equatorial forests host extraordinary endemism. Signature mammals include the Bornean orangutan, Borneo pygmy elephant, proboscis monkey, Bornean clouded leopard and sun bear. Birdlife features hornbills and pittas; flora includes Rafflesia species and diverse pitcher plants Nepenthes. Many species are endangered due to habitat loss and fragmentation; orangutans and elephants are conservation flagships, and crocodiles, pit vipers and the king cobra represent notable hazards. Strict rules govern wildlife trade and export, with permits required and enforcement tightened; domesticated animals are common in settlements, but bringing animals across borders requires health certificates and quarantine. Several species appear in national Red Lists and are protected within parks and forest reserves.

Religion and races
Religious and ethnic mosaics vary by state. Muslims form majorities in Brunei and across much of Sabah and Kalimantan; Christianity is strong among Dayak and in Sarawak and interior Sabah; Chinese communities often practice Buddhism, Taoism or Christianity. English, Malay and Indonesian facilitate interethnic communication. In broad terms, Islam and Christianity are the leading faiths, with indigenous beliefs integrated into festivals. Traditions emphasize hospitality in longhouses, harvest rituals such as Kaamatan and Gawai, modest dress in rural and religious settings, and respect for elders.

Wars and conflicts
World War II battles and occupation left memorials at Sandakan and Labuan. The 1962 Brunei revolt and the 1963-66 Indonesia-Malaysia Confrontation marked the Cold War era; Sarawak and Sabah faced communist insurgencies into the 1980s. In 2013 an armed incursion by Sulu militants in Lahad Datu, Sabah, led to security reforms and the creation of a special security zone. Today the island is not a war theater, though maritime security concerns persist in the Sulu-Sulawesi seas; counterterrorism and coastal patrols are ongoing. War cemeteries and memorials are maintained in Sabah, Sarawak and Brunei.

Quality of life
Standards differ across borders. Brunei ranks among Southeast Asia’s highest in income and social services. Malaysian Borneo offers solid infrastructure in cities with varying rural access. Indonesian Kalimantan is developing rapidly with new roads and services but retains large remote areas. Corruption perceptions vary by country, generally lower in Brunei and higher in parts of Indonesia; urban centers provide better public services than the interior.

Healthcare
Major hospitals serve Kuching, Kota Kinabalu and Bandar Seri Begawan; Indonesian provincial capitals provide public and private hospitals. Pharmacies are common in cities and towns, with 24-hour options in larger urban areas. Travelers should consider vaccines for Hepatitis A, Typhoid, Tetanus-diphtheria, and Hepatitis B, and consult malaria prophylaxis for remote Kalimantan and interior Sabah-Sarawak. Dengue is present islandwide; drink bottled or treated water and practice mosquito protection.

Sports
Football and badminton dominate, alongside sepak takraw, pencak silat, and dragon boat racing. The Borneo Marathon runs in Kota Kinabalu; mountain running around Kinabalu was once showcased in the Kinabalu Climbathon. Divers flock to Sipadan and the Semporna archipelago, while caving and spelunking thrive in Mulu. National athletes from these states contribute to Malaysian and Indonesian teams at regional and Olympic levels.

Holidays
Key observances include Hari Raya Aidilfitri and Aidiladha for Muslims, Chinese New Year, Christmas for Christians, and state festivals: Kaamatan in Sabah on May 30-31, Gawai Dayak in Sarawak on June 1-2, Brunei National Day on February 23, Malaysia Day on September 16, and Indonesia’s Independence Day on August 17. Local city and state days add to the calendar.

Traditions
Shoes off when entering homes and longhouses. Use the right hand for giving and receiving. Dress modestly in villages and at religious sites; alcohol is restricted or discouraged in many settings, and in Brunei public consumption is prohibited for everyone. Always ask before photographing people or sacred objects; offer small gifts when hosted in longhouses.

Interesting facts
The equator crosses Borneo at Pontianak, commemorated by an Equator Monument. Kinabalu at 4095 m is one of Southeast Asia’s highest peaks outside the Himalayas. Gunung Mulu’s Sarawak Chamber is among the largest known cave chambers on Earth. Sipadan is a world top-tier dive site praised by Jacques Cousteau. The Brooke dynasty in Sarawak created the unique legacy of the White Rajahs. The 2015 Sabah earthquake shook Kinabalu’s granite spires. Films and documentaries often feature Borneo’s wildlife and longhouses, including productions shot in Sarawak’s forests and along the Kinabatangan.

Money
Currencies differ: Malaysian ringgit in Sabah and Sarawak, Brunei dollar in Brunei (interchangeable at par with the Singapore dollar), and Indonesian rupiah in Kalimantan. ATMs are widespread in cities; cards are accepted in hotels, malls and many restaurants, less so in remote areas and national parks. Typical exchange rates fluctuate, but as a guide 1 USD is roughly MYR 4.5, BND 1.35 and IDR 15,500. Exchange money at banks and licensed changers in cities; in Brunei banks offer competitive rates. Pay by card where available, carry cash for rural travel. Tipping is not customary in Brunei, modest and appreciated in Malaysia and Indonesia.

Everyday details
Electricity is 240 V 50 Hz with Type G plugs in Malaysia and Brunei; 230 V 50 Hz with Type C and F plugs in Indonesia. Mobile coverage is strong in cities with 4G and expanding 5G in some urban areas; patchy in the interior. Smoking is restricted in many public indoor spaces in Malaysia and Brunei; Indonesia’s rules vary by locality with designated smoking areas.

Clothing
Dress for heat and humidity year-round: breathable fabrics, sun protection and rain layers. Shorts and short skirts are fine in cities and resorts, but cover shoulders and knees in villages and religious places. Open-toe footwear is common; head coverings are required only inside mosques and by custom at some ceremonies.

Tourism
Plan 10-14 days to sample highlights across one or two regions, or 3-4 weeks for a fuller loop. Classic routes include Sabah’s Kota Kinabalu-Kinabalu Park-Kundasang-Danum Valley or Kinabatangan-Semporna for Sipadan diving; Sarawak’s Kuching-Bako-Mulu longhouses and caves; Brunei’s Bandar Seri Begawan mosques, Kampong Ayer stilt village and Ulu Temburong rainforest; and Kalimantan’s Tanjung Puting orangutan river cruises or Derawan-Maratua atolls. Logistics often mix flights with 4WD transfers and boats; book park permits for Sipadan, Mulu and Kinabalu well in advance. Eco-lodges, community stays and guided jungle treks enrich wildlife viewing and cultural immersion.

Types of tourism
Wildlife watching, jungle trekking, caving, scuba diving and snorkeling, river cruises, cultural longhouse stays, city heritage walks, birding, mountain hiking and highland retreats, photography and gastronomy with Indigenous and Malay-Chinese influences.

Tourist attractions
– Kinabalu Park – Malaysia’s first UNESCO World Heritage site centered on Mount Kinabalu
– Gunung Mulu National Park – UNESCO site famed for caves and karst pinnacles
– Sipadan Island – world-class dive walls and pelagics, access via permits
– Danum Valley Conservation Area – primary lowland rainforest and research center
– Kinabatangan River – proboscis monkeys, pygmy elephants and river lodges
– Bako National Park – coastal rainforest, proboscis monkeys, beaches and trails
– Ulu Temburong National Park – Brunei’s pristine rainforest with canopy walk
– Tanjung Puting National Park – Indonesian orangutan rehabilitation and klotok cruises
– Derawan and Maratua Islands – reefs, manta cleaning stations and marine lakes
– Niah Caves – archaeology and massive caverns near Miri

Non-tourist attractions
– Bintulu LNG Complex – one of the region’s largest LNG export hubs
– Seria Oil Field – Brunei’s historic onshore oil production heart
– Balikpapan Refinery – Indonesian refining and petrochemical center
– Palm Oil Mills and Estates – extensive agro-industrial landscapes across lowlands
– Bakun Hydroelectric Dam – major hydropower project in Sarawak’s interior

Local cuisine
Expect Malay, Chinese, Indigenous and Indonesian flavors: Sarawak laksa with prawn broth, kolo mee springy noodles, ambuyat sago starch in Brunei, hinava citrus-marinated fish in Sabah, ayam pansuh bamboo-cooked chicken, midin jungle fern and kek lapis layered cake. Alcohol is available in Malaysian Borneo and parts of Kalimantan but prohibited for sale to Muslims and restricted in Brunei, where non-Muslims may import limited personal quantities. Meals follow regional norms: breakfast from 7-9, lunch 12-14, dinner 19-21. Tipping is modest or included via service charge; choose busy stalls, eat freshly cooked food, and prefer bottled water.

Why visit
Borneo fuses megadiversity with living cultures and accessible adventure. In a single trip you can summit alpine granite, glide by crocodile banks at dusk, dive vertical walls, sleep in longhouses and listen to gibbons at dawn.

Safety for tourists
Urban areas are generally safe with standard precautions against petty theft. Wildlife hazards include crocodiles along estuaries and rivers, venomous snakes, stinging marine life and leeches in rainforest. Terrorism risk is low but coastal eastern Sabah has a history of kidnappings; heed current advisories and stay within security zones. Infectious risks include dengue and, in some rural areas, malaria and leptospirosis. Rabies outbreaks have occurred in parts of Sarawak; avoid contact with stray animals. Emergency numbers: Malaysia 999 or 112, Brunei ambulance 991, police 993, fire 995, Indonesia 112 with local services via 110 police and 118-119 medical.

Tourist infrastructure level
Service levels are high in Malaysian Borneo and Brunei for hotels and restaurants, with English widely spoken. Indonesian Kalimantan ranges from solid urban hotels to simple guesthouses in remote areas, with variable English; guides ease logistics. Park facilities at Kinabalu and Mulu are well organized with booking systems.

Entry rules
Visas depend on the country: many nationalities enter Malaysia visa-free, Brunei offers visa-free or visa-on-arrival to select passports, and Indonesia extends e-visa on arrival to many travelers. Passports must be valid for at least 6 months. Customs prohibit drugs and weapons; Brunei enforces strict alcohol limits for non-Muslims and bans pornographic material. Declare drones and obtain permits where required, especially in national parks and near borders.

Transport
Air travel links main cities; turboprops connect interior strips in Malaysian Borneo. Long-distance buses, minibuses and ride-hailing apps operate in cities. Boats ply major rivers such as the Kapuas and Mahakam and connect coastal islands. Ferries link Sabah to Labuan and Brunei; in Kalimantan, riverboats remain vital. Tickets are commonly purchased online in Malaysia and Brunei and via local apps and counters in Indonesia.

Car
Driving is on the left across the island. International Driving Permits are recommended. Roads are paved between cities but can be rough in interiors; 4WD is advisable for logging roads and park access. Speed limits generally 50-60 km/h urban, 80-100 km/h interurban depending on jurisdiction; enforcement via speed cameras in cities. DUI laws are strict with heavy penalties. Tolls are limited compared to Peninsular Malaysia. Parking is metered or coupon-based in cities. Dashcams are common; no winter tires are needed. Police corruption is uncommon in Malaysia and Brunei and varies in Indonesia; remain polite and keep documents handy.

Quiet hours
Residential quiet hours typically run from late evening to early morning, often 22:00-07:00, though exact rules vary by municipality and accommodation. Expect early morning calls to prayer in Muslim neighborhoods.

Daily budget
Indonesia Kalimantan – budget 550,000-800,000 IDR per day or 35-50 USD; mid-range 1.2-2.0 million IDR or 75-125 USD.
Malaysia Sabah and Sarawak – budget 200-320 MYR per day or 45-70 USD; mid-range 350-600 MYR or 75-130 USD.
Brunei – budget 110-160 BND per day or 80-120 USD; mid-range 160-250 BND or 120-185 USD.

What not to do
Do not remove or purchase wildlife or products like hornbill parts or turtle shells. Avoid flying drones without permits, especially over people, military sites and parks. Do not drink alcohol in public in Brunei and respect local religious norms across the island. Do not trespass in longhouses or sacred sites; always request permission.

Climate
Equatorial and humid year-round with temperatures mostly 23-32 C at low elevations. Rain falls in all months with wetter periods varying by coast; seas are generally calmest around April-May and September-October for diving in Sabah. Highlands like Kinabalu are cool, and interiors can experience intense downpours leading to swollen rivers.

Tips for travelers
Carry insect repellent, a lightweight rain jacket, electrolyte packets and leech socks for jungle treks. Vaccinations for Hep A, Typhoid and Tetanus are sensible; consider malaria prophylaxis for remote trips. Book limited-visitor sites like Sipadan, Mulu caves and Kinabalu climbs well ahead. Respect park rules, hire certified guides for jungle routes and diving, and keep copies of travel documents for multi-border itineraries.