Global vegetation map. Darkest places are rainforest

Olympic rain forest in Olympic Peninsula, Washington state

Borneo rainforest

A rainforest is a forest that gets heavy rainfall. The most notable rainforests are in the tropics or subtropics. The biggest rainforest is the Amazon rainforest, which is mostly in Brazil.

Forests like this have extraordinary biodiversity. Over half of all plant and animal species live in the rainforest. Also more than 1/4 of all medicines come from here. They are an important source of oxygen, but not so much as the seas.