Yasuní: The Most Biodiverse Forest on Earth, and the Oil Ecuador Voted to Leave Beneath It

Yasuní National Park and the Yasuní Biosphere Reserve lie in the Amazon of eastern Ecuador, in the provinces of Orellana and Pastaza, where the Equator, the Andes, and the Amazon meet. The park is one of the most biologically diverse places on Earth, a sanctuary for Indigenous peoples, and the site of one of Latin America's most closely watched conflicts between conservation and oil.

Location and Extent

Yasuní lies between the Napo and Curaray rivers, about 250 km (160 mi) from Quito. It was established as a national park on July 26, 1979, and in 1989 UNESCO designated it a Biosphere Reserve together with the adjacent Waorani Ethnic Reserve. The park is the reserve's core area and covers 9,820 sq km (3,780 sq mi); the reserve as a whole, including buffer and transition zones, extends to 16,820 sq km (6,494 sq mi). It sits in the Napo Basin, a funnel-shaped basin that begins in the eastern Ecuadorian Andes and runs southeast to the Napo's confluence with the Amazon in Peru, part of the wider upper Amazon Basin.

Map depicting the location of Yasuní National Park.

Climate, Topography, and Soils

Yasuní is hot, humid, and very wet. Annual rainfall reaches up to 3,800 mm (150 in), with two wet seasons, March to July and October to November. July is typically the wettest month, at about 400 mm (15.75 in), and December the driest, at about 130 mm (5 in). The mean annual temperature is 25.5°C (77.9°F), and relative humidity stays between 83% and 90% all year.

Despite lying in the Amazonian lowlands, the terrain is surprisingly sinuous, with low plains interspersed with foothills of the Andean Cordillera. Most rivers other than the Napo rise at 300 to 600 m (1,000 to 2,000 ft), including the Tiputini, Cononaco, and Nashiño. The soils blend older material from the Guiana Shield with Quaternary sediments washed down from the Andes, and the region is classified as a Pleistocene refuge, a place where forest persisted through the dry, cool periods of the last ice age and where new species evolved as a result.

Ecosystems

Yasuní is predominantly humid tropical rainforest in the Napo moist forests ecoregion, with three main vegetation types. Terra firme forest covers the higher ground that never floods, várzea forest is periodically flooded by rivers, and igapó occupies areas that are permanently or nearly permanently flooded. Together they support a complex web of life and much of the reserve's ecological balance.

Biodiversity: A Collection of World Records

Yasuní holds world records for local-scale richness of trees, amphibians, and bats, and is among the richest places anywhere for birds and mammals. More than 650 tree species have been counted in a single hectare, more than occur across the United States and Canada combined, and estimates for insects run as high as 100,000 species per hectare. It is also one of only nine places on Earth with more than 4,000 vascular plant species per 10,000 sq km. More than 2,000 plant species have been documented in the park, and the biosphere reserve as a whole is credited with about 4,000.

The forest has the layered structure of a mature Amazonian rainforest, with a dense canopy, an understory of shrubs and small trees, and a leaf-littered floor. Kapok (Ceiba pentandra) and numerous palms are among the characteristic trees, and epiphytes, including orchids, festoon the branches.

Yasuní supports between 170 and 200 mammal species, including the jaguar (Panthera onca), the apex predator; the giant otter (Pteronura brasiliensis); the lowland tapir (Tapirus terrestris); the giant armadillo (Priodontes maximus); and the Amazon river dolphin (Inia geoffrensis) in its rivers. At least a dozen primate species occur here, including the golden-mantled tamarin (Saguinus tripartitus), the pygmy marmoset (Cebuella pygmaea), and Poeppig's woolly monkey (Lagothrix poeppigii), all important seed dispersers.

Nearly 600 bird species have been recorded, including the harpy eagle (Harpia harpyja) and the endangered wattled curassow (Crax globulosa), along with about 150 amphibian species, 121 reptile species, and roughly 380 fish species. Poison dart frogs (Dendrobatidae) are among the most striking amphibians, and the green anaconda (Eunectes murinus) is among the largest of the reptiles.

The Waorani and the Peoples in Isolation

Yasuní lies within the ancestral territory of the Waorani, and Kichwa and Shuar communities also live in and around the reserve. It is also home to the Tagaeri and Taromenane, the only two Indigenous peoples officially recognized as living in isolation in Ecuador. Both are eastern Waorani groups; the Tagaeri separated from other Waorani in 1968 after refusing missionary settlement, and estimates put the Taromenane at 150 to 300 people. In 1999, the government created the Tagaeri-Taromenane Intangible Zone (ZITT) to shield them from outside contact, but oil blocks surround it and, in places, overlap it.

Violent episodes in 2003, 2006, and 2013 killed dozens of Tagaeri and Taromenane. At least two of these were attributed to members of the Waorani nation, and lawyers for the isolated peoples argue that logging and oil operations raised tensions and pressure on their territory, a claim the Ecuadorian government has disputed. In March 2025, the Inter-American Court of Human Rights ruled that Ecuador had violated the rights of the Tagaeri and Taromenane, its first ruling on a people living in voluntary isolation.

Elsewhere in the reserve, the Cononaco River region is a traditional settlement area for Waorani and Kichwa communities. More than 9,800 people live in the reserve, farming coffee, bananas, yuca, papaya, citrus, maize, and achiote; fishing, hunting, and gathering forest products; and using the rivers as their main travel routes. The Tiputini Biodiversity Station, on the northern bank of the Tiputini River in Orellana Province, is a major research center within the reserve.

Oil in the Park: The 2023 Referendum

Oil extraction began in Ecuador's Amazon in 1972, and three oil blocks lie within Yasuní: Block 16, in decline; Block 31, with little crude; and Block 43, known as ITT for its Ishpingo, Tambococha, and Tiputini fields. In 2007, President Rafael Correa launched the Yasuní-ITT Initiative, offering to keep the oil in the ground if the international community contributed US$3.6 billion. The plan was abandoned in 2013, and drilling in ITT began in 2016.

After a decade of campaigning by the Yasunidos coalition, Ecuadorians voted on August 20, 2023, on whether the government should keep the ITT crude underground indefinitely. About 58% voted yes, more than 5.2 million people, and the result gave Petroecuador one year to withdraw and barred new exploration contracts. Petroecuador's manager warned of losses of nearly US$14 billion over 20 years, and the government has argued that an orderly closure will take years.

Three years on, the oil is still flowing. Block 43 was still producing around 40,000 barrels per day in 2026, roughly a tenth of national output in 2025, and had fallen only 3.6% year on year in the first four months of 2026. Only a handful of wells had been closed by early 2025. Human Rights Watch documented that operations continued through 2025 despite the March 2025 Inter-American Court order to stop them, and in early September 2026 a fuse failure at a plant in the block briefly shut down 161 wells, with no spill reported. Waorani and other Indigenous leaders continue to press for implementation, while the case tests whether a national vote and an international court can end oil extraction inside a protected area.

Other Threats and Conservation

Beyond oil, Yasuní faces deforestation, illegal logging, and hunting, all of which fragment habitat, and climate change adds further pressure. The biosphere reserve was established to integrate conservation with sustainable development, and international organizations, NGOs, and local communities collaborate on protected-area management and community-based conservation.

Ecotourism is a growing conservation tool, with lodges and guided tours offering visitors an immersive rainforest experience, though entry requires permission. Responsible tourism that reinvests in community development can provide an alternative livelihood for Waorani and Kichwa communities and build support for protecting the forest.

Conclusion

Yasuní holds some of the highest concentrations of life ever recorded and is home to peoples who have chosen to live apart from the modern world. It also sits above oil that Ecuadorians voted to leave in the ground. Whether the vote is carried out will decide what Yasuní's biodiversity records are worth, and whether the Tagaeri and Taromenane can keep the isolation that a court has now said Ecuador must protect.