The Kon-Tiki raft, used by the Norwegian explorer Thor Heyerdahl, was made of which tree?

The Kon-Tiki expedition was a 1947 journey by raft across the Pacific Ocean from South America to the Polynesian islands, led by Norwegian explorer and writer Thor Heyerdahl. The raft was named Kon-Tiki after the Inca sun god, Viracocha, for whom "Kon-Tiki" was said to be an old name.

Heyerdahl believed that people from South America could have settled Polynesia in pre-Columbian times. His aim in mounting the Kon-Tiki expedition was to show, by using only the materials and technologies available to those people at the time, that there were no technical reasons to prevent them from having done so. Although the expedition carried some modern equipment, such as a radio, watches, charts, sextant, and metal knives, Heyerdahl argued they were incidental to the purpose of proving that the raft itself could make the journey.

The main body of the float was composed of nine balsa tree trunks up to 14 m (45 ft) long, 60 cm (2 ft) in diameter.