Kon-Tiki is the raft used by Norwegian explorer and writer Thor Heyerdahl in his 1947 expedition across the Pacific Ocean from South America to the Polynesian islands. It was named after the Inca sun god, Viracocha, for whom "Kon-Tiki" was said to be an old name. Kon-Tiki is also the name of the popular book that Heyerdahl wrote about his adventures.
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, these were argued to be incidental to the purpose of proving that the raft itself could make the journey.)
The Kon-Tiki expedition was funded by private loans, along with donations of equipment from the United States Army. Heyerdahl and a small team went to Peru, where, with the help of dockyard facilities provided by the Peruvian authorities, they constructed the raft out of balsa logs and other native materials in an indigenous style as recorded in illustrations by Spanish conquistadores. The trip began on April 28, 1947. Heyerdahl and five companions sailed the raft for 101 days over 4,300 miles across the Pacific Ocean before smashing into a reef at Raroia in the Tuamotu Islands on August 7, 1947. The crew made successful landfall and all returned safely.
Thor Heyerdahl's book about his experience became a bestseller. It was originally published in 1950 as The Kon-Tiki Expedition: By Raft Across the South Seas, later reprinted as Kon-Tiki: Across the Pacific in a Raft. A documentary motion picture about the expedition, also called Kon-Tiki was produced from a write-up and expansion of the crew's filmstrip notes and won an Academy Award in 1951. It was directed by Thor Heyerdahl and edited by Olle Nordemar. The voyage was also chronicled in the documentary TV-series The Kon-Tiki Man: The Life and Adventures of Thor Heyerdahl, directed by Bengt Jonson.
The Kon-Tiki was crewed by six men, all Norwegian except for Bengt Danielsson, who was from Sweden.
- Thor Heyerdahl (1914–2002) was expedition leader.
- Erik Hesselberg (1914–1972) was the navigator and artist. He painted the large Kon-Tiki figure on the raft's sail.
- Bengt Danielsson (1921–1997) took on the role of steward, in charge of supplies and daily rations. Danielsson was a Swedish sociologist interested in human migration theory. He also served as translator, as he was the only member of the crew who spoke Spanish.
- Knut Haugland (1917–2009) was a radio expert, decorated by the British in World War II for actions in the Norwegian heavy water sabotage that stalled what were believed to be Germany's plans to develop an atomic bomb.
- Torstein Raaby (1920–1964) was also in charge of radio transmissions. He gained radio experience while hiding behind German lines during WWII, spying on the German battleship Tirpitz. His secret radio transmissions eventually helped guide in Allied bombers to sink the ship.
- Herman Watzinger (1910–1986) was an engineer whose area of expertise was in technical measurements. He recorded meteorological and hydrographical data while underway.
The main body of the raft was composed of nine balsa tree trunks up to 13.7 metres (45 ft) long, 60 cm (2 ft) in diameter, lashed together with 3.175 cm (1¼ inch) hemp ropes. Cross-pieces of balsa logs 5.5 m (18 ft) long and 30 cm (1 ft) in diameter were lashed across the logs at 1 m (3 ft) intervals to give lateral support. Pine splashboards clad the bow, and lengths of pine 2.5 cm (1 inch) thick and 60 cm (2 ft) wide were wedged between the balsa logs and used as centerboards.
The main mast was made of lengths of mangrove wood lashed together to form an A-frame 8.8 m (29 ft) high. Behind the main-mast was a cabin of plaited bamboo 4.2 m (14 ft) long and 2.4 m (8 ft) wide was built about 1.21-1.51 m (4-5 feet) high, and roofed with banana leaf thatch. At the stern was a 5.8 m (19 ft) long steering oar of mangrove wood, with a blade of fir. The main sail was 4.6 m by 5.5 m (15 by 18 feet) on a yard of bamboo stems lashed together. Photographs also show a top-sail above the main sail, and also a mizzen-sail, mounted at the stern.
The raft was partially decked in split bamboo. The main spars were a laminate of wood and reeds and Heyerdahl tested more than twenty different composites before settling on one that proved an effective compromise between bulk and torsional rigidity. No metal was used in the construction.
The Kon-Tiki carried 250 litres of water in bamboo tubes. For food they took 200 coconuts, sweet potatoes, bottle gourds and other assorted fruit and roots. The U.S. Army Quartermaster Corps provided field rations, tinned food and survival equipment. In return, the Kon-Tiki explorers reported on the quality and utility of the provisions. They also caught plentiful numbers of fish, particularly flying fish, "dolphin fish", yellowfin tuna, bonito and shark.
The expedition, with the amateur radio call sign of LI2B, maintained regular communication with a number of American, Canadian, and South American stations that kept the Norwegian Embassy in Washington, D.C., abreast of Kon-Tiki's efforts. The success of these contacts was due to the skill of former World War II Norwegian underground radio operators, Knut Haugland, and Torstein Raaby. On August 5, Haugland contacted Oslo, Norway, for a circuit of about 10,000 miles. 
The expedition carried three watertight radio transmitters. The first operated on the 40- and 20-meter bands, the second on the 10-meter band, and the third on the 6-meter band. Each unit was made up entirely of 2E30 vacuum tubes providing 10 watts of RF input. As an emergency backup they also carried a German Mark V transceiver originally re-created by the SOE in 1942. Power was supplied by batteries and a hand-cranked generator. 
The Kon-Tiki's radio receiver was a National Radio Company NC-173. In his book Kon-Tiki (Rand-McNally 1950, p. 263), Heyerdahl describes the NC-173 slowly drying out on an uninhabited South Sea island after getting soaked in a shipwreck, gradually receiving at higher and higher frequencies until eventually settling on the 13.990 MHz frequency needed to make contact.  The crew used their hand-cranked emergency transmitter to send out an "all well, all well" message via LI2B just in time to head off a massive rescue attempt. 
The Kon-Tiki left Callao, Peru, on the afternoon of April 28, 1947. It was initially towed 50 miles out to open water by the Fleet Tug Guardian Rios of the Peruvian Navy. The ship then sailed roughly west carried along on the Humboldt Current. The crew's first sight of land was the atoll of Puka-Puka on July 30. They made brief contact with the inhabitants of Angatau Island on August 4, but were unable to land safely. Incidentally, the Angatau atoll was reached after 97 days of travel, the calculated absolute minimum navigational time to reach Polynesia.
Three days later, on August 7, the raft struck a reef and was eventually beached on an uninhabited islet off Raroia Island in the Tuamotu group. The team had travelled a distance of around 3,770 nautical miles (c. 6980 km) in 101 days, at an average speed of 1.5 knots.
After spending a number of days alone on the tiny islet, the crew were greeted by men from a village on a nearby island who arrived in canoes, having seen washed-up flotsam from the raft. The crew were taken back to the native village, where they were feted with traditional dances and other festivities. Finally the crew were taken off Raroia to Tahiti by the French schooner Tamara, with the salvaged Kon-Tiki in tow.
On April 28, 2006, a Norwegian team attempted to duplicate the Kon-Tiki voyage using a newly built raft, the Tangaroa, named after the Māori sea-god Tangaroa. Again based on records of ancient vessels, this raft used relatively sophisticated square sails that allowed sailing into the wind, or tacking. It was 16m long by 8m wide. It also included a set of modern navigation and communication equipment, including solar panels, portable computers, and desalination equipment. The crew posted to their web site.  The crew of six was led by Torgeir Higraff, and included Olav Heyerdahl, grandson of Thor Heyerdahl. The voyage was completed successfully in July 2006 and a documentary film is forthcoming.
- Experimental archaeology
- Kantuta Expeditions a repeated expeditions of Kon-Tiki by Eduard Ingriš
- Polynesian navigation
- Tupac Inca Yupanqui
- William Willis in 1954 sailed on a raft from Peru to American Samoa alone
- The Kon-Tiki Man episode breakdown
- An LA, as in Norway, Story, by Bob Merriam, W1NTE, March 5, 2003
- Thor Heyerdahl of Kon-Tiki fame dies at 87, April 24, 2002,
- An LA, as in Norway, Story, by Bob Merriam, W1NTE, March 5, 2003
- Boatanchor Pix, National NC-173
- Thor Heyerdahl of Kon-Tiki fame dies at 87 April 24, 2002,
- Vecchio, Rick (2006-04-29). "Norwegian team embarks on 'Kon-Tiki' trip". Associated Press via San Jose Mercury News. http://www.mercurynews.com/mld/mercurynews/news/world/14456054.htm. Retrieved 2006-05-02.
- Heyerdahl, Thor (1950). Kon-Tiki. Rand McNally & Company. At Internet Archive.
- Hesselberg, Erik (1950). Kon-Tiki and I : illustrations with text, begun on the Pacific on board the raft "Kon-Tiki" and completed at "Solbakken" in Borre. Allen & Unwin
- Kon-Tiki Museum
- National NC-173 receiver
- Quick Facts: Comparing the Two Rafts: Kon-Tiki and Tangaroa Azerbaijan International, Vol 14:4 (Winter 2006)
- Testing Heyerdahl's Theories about Kon-Tiki 60 Years Later: Tangaroa Pacific Voyage (Summer 2006) Azerbaijan International, Vol 14:4 (Winter 2006)
- Kon-Tiki in Reverse: The Tahiti-Nui Expedition
- TV2Sumo WebTV programme "Ekspedisjonen Tangaroa" (Tangaroa Expedition) - Norsk
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