Ochroma pyramidale, commonly known as balsa, is a large, fast-growing tree native to the Americas. It is the sole member of the genus Ochroma, and is classified in the subfamily Bombacoideae of the mallow family Malvaceae. The tree is famous for its wide usage in woodworking, due to its softness and its high strength compared to its low density. The name balsa is the Spanish word for "raft" and the Portuguese word for ferry.

A deciduous angiosperm, Ochroma pyramidale can grow up to 30 metres (100 feet) tall, and is classified as a hardwood despite the wood itself being very soft; it is the softest commercial hardwood and is widely used because of its light weight.

Balsa trees grow extremely fast, often up to 27 metres (90 feet) in 10–15 years, and do not usually live beyond 30 to 40 years. In terms of volume (as opposed to height) they may be the fastest growing tree known; Streets mentions one individual which grew 11.2 m (37 ft) tall and 17 cm (6.7 in) diameter at breast height during a period of fifteen months. Balsa, like most rainforest trees, does not make annual rings, but this growth is equivalent to rings 7 cm (2.8 in) wide. They are often cultivated in dense patches, with Ecuador supplying 95% or more of the commercial balsa. The wood from these trees is highly valuable due to its high strength-to-weight ratio, which is achieved through a kiln-drying process that leaves the wood's cells hollow and empty.

Balsa wood is popular for light, stiff structures in model bridge tests, model buildings, and construction of model aircraft. It is also used in the manufacturing of wooden crankbaits for fishing, makeshift pens for calligraphy, composites, surfboards, boats, "breakaway" props for theatre and television, and even in the floor pans of the Chevrolet Corvette. Balsa wood played a historical role in Thor Heyerdahl's Kon-Tiki expedition where it was used to build the raft. Balsa wood is also popular in arts such as whittling, and in the making of baroque-style picture frames due to its ease of shaping.

A member of the mallow family, Ochroma pyramidale is native from southern Mexico to southern Brazil, but has been introduced to many other countries, including Papua New Guinea, Indonesia, Thailand, and the Solomon Islands. It is a pioneer plant, which establishes itself in clearings in forests, either man-made or where trees have fallen, or in abandoned agricultural fields. It grows extremely rapidly, up to 27 metres (90 ft) in 10–15 years. The speed of growth accounts for the lightness of the wood, which has a lower density than cork. Trees generally do not live beyond 30 to 40 years.

Flowers are produced from the third year onwards, typically at the end of the rainy season when few other trees are in flower. The large flowers, up to 20 cm (8 in) in diameter, open in the late afternoon and remain open overnight. Each may contain a pool of nectar up to 2.5 centimetres (1 in) deep. Daytime pollinators include capuchin monkeys. However, most pollination occurs at night; the main pollinators were once thought to be bats, but recent evidence suggests that two nocturnal arboreal mammals, the kinkajou and the olingo, may be the primary pollinators.

It is evergreen or dry-season deciduous, with large 30 to 40 centimetres (12 to 16 in), weakly palmately lobed leaves.

Being a deciduous angiosperm, balsa is classified as a hardwood despite the wood itself being very soft; it is the softest commercial hardwood.