Ochroma pyramidale, commonly known as the balsa tree, is a large, fast-growing tree native to the Americas. It is the sole member of the genus Ochroma. The tree is famous for its wide usage in woodworking, with the name balsa being the Spanish word for "raft."A deciduous angiosperm, Ochroma pyramidale can grow up to 30 m 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.

Thor Heyerdahl (Norwegian pronunciation: [tuːr ˈhæ̀ɪəɖɑːɫ]; 6 October 1914 – 18 April 2002) was a Norwegian adventurer and ethnographer with a background in zoology, botany and geography.

Heyerdahl is notable for his Kon-Tiki expedition in 1947, in which he sailed 8,000 km (5,000 mi) across the Pacific Ocean in a hand-built raft from South America to the Tuamotu Islands. The expedition was designed to demonstrate that ancient people could have made long sea voyages, creating contacts between societies. This was linked to a diffusionist model of cultural development.

Heyerdahl made other voyages to demonstrate the possibility of contact between widely separated ancient peoples, notably the Ra II expedition of 1970, when he sailed from the west coast of Africa to Barbados in a papyrus reed boat. He was appointed a government scholar in 1984.

He died on 18 April 2002 in Colla Micheri, Liguria, Italy, while visiting close family members. The Norwegian government gave him a state funeral in Oslo Cathedral on 26 April 2002.In May 2011, the Thor Heyerdahl Archives were added to UNESCO's Memory of the World Register. At the time, this list included 238 collections from all over the world. The Heyerdahl Archives span the years 1937 to 2002 and include his photographic collection, diaries, private letters, expedition plans, articles, newspaper clippings, original book, and article manuscripts. The Heyerdahl Archives are administered by the Kon-Tiki Museum and the National Library of Norway in Oslo.