Rainforests are likely Earth's oldest living ecosystems. They grow on every continent except Antarctica, and tropical rainforests are found in Central and South America and in Africa. The largest rainforests on Earth surround the Amazon River in South America and the Congo River in Africa. The largest unbroken stretch of rainforest is in the Amazon river basin of South America, which spans at least 6 million square kilometers (2.3 million square miles), nearly twice the size of India. As of November 2026, the rainforest covers about 80 percent of the basin, and just over half of the world's rainforests are in the Neotropical realm, about a quarter in Africa and about a fifth in Asia.
As of November 2026, the Amazon rainforest is home to around 40,000 plant species, nearly 1,300 bird species and 3,000 types of fish, and it has more than 430 species of mammals and 2.5 million different insects. As of November 2026, the Amazon has an estimated 400 billion trees, and it is home to about 10 percent of the world's known species. Tropical wet forests have more species of trees than any other biome, and a single hectare (2.5 acres) of tropical rainforest can hold hundreds of species of trees. The Amazon is the largest river on Earth by the volume of water it carries, and as of November 2026 its flow is about 15 percent of all the fresh water that rivers discharge into the oceans.
Scientists did not know of okapis until 1901. The okapi, a rainforest animal of the Congo, is the only close living relative of the giraffe, and okapis live in tropical rainforests in the northeast region of the Democratic Republic of the Congo. Bats are the most diverse mammals in most tropical rainforests, and lizards, snakes and frogs have their greatest diversity in the rain forest, including many groups found only there. Poison dart frogs live in the wet tropical forests of Central and South America. Frogs raised on a diet of crickets and other non-poisonous insects in human care are not poisonous themselves.
As of July 2023, about 2.5 million Indigenous people live in the Pan Amazon region of South America. About 90 percent of all natural rubber comes from the Brazilian rubber tree as of November 2026, and the Brazilian rubber tree is native to the Amazon Basin. Chocolate is made from the beans of the cacao tree, and the cacao tree comes from the Amazon region of South America. As of November 2026, about a quarter of the medicines used today come from plants found in tropical rainforests, and the medicinal value of the plant world in the tropics is underexplored.
In the 1970s, advances were made in reaching the forest canopy by using mountaineering techniques with ropes. Canopy researchers can now use cranes, canopy walkways, ultra-lite planes, dirigible balloons and balloon-rafts, and canopy walkways are one of the popular and practical ways for scientists to reach the forest canopy. A canopy crane in Ecuador's Yasuni National Forest lifts visitors 140 feet off the ground for 360-degree views. Canopy leaves act as trillions of tiny solar panels, turning strong sunlight into energy. A scientist compares every giant tree in the Amazon canopy to an island in an ocean of trees.
An estimated 40% of all land species are found at a height of 20 meters and higher. As of November 2026, scientists are still finding new species in tropical rainforests. National Geographic Explorer Meg Lowman has said that we know more about the moon than we do about the Amazon forest canopy. A National Geographic writer says forest crown science is in its infancy. As of November 2026, the biodiversity of tropical rainforests is still largely unknown to science.
Words to know
- ecosystems: living communities
- basin: river's land area
- canopy: top leafy layer
- biodiversity: variety of life
- medicinal: used as medicine
