Mobile version

Satellites shed light on the Kon Tiki story

Image of the month - August 2005

In April 1947, Thor Heyerdhal crossed the Pacific on a balsa raft called the Kon Tiki, to prove that it would have been possible for South America and Polynesia to have made contact a long time ago. While altimetric satellites (or any others for that matter) didn't exist at the time, it is possible to use them today to get a better understanding of the journey taken by the Kon Tiki.
The crossing was relatively fast: barely 3 months to cover the 7,700 km that separate Peru from the Tuamotu Islands. Heyerdhal noted that the raft was never driven back towards South America, and that the average speed was 42.5 nautical miles per day (about 75 km/day), with the help of the Trade Winds. Therefore, if 1947 (like 1948) had been an El Niño year, the Kon Tiki would probably not have completed the crossing as the winds would have been too weak or might even have blown the other way.
During its crossing the raft was deflected towards the South on several occasions. Onboard measurements revealed colder waters. Looking at this zone from satellites, we see the quasi-systematic presence of turbulence brought about by the meeting of a strip of cold water at the equator with the South-equatorial current, which creates cold currents towards the South (South of the equator). These Tropical Instability Waves are probably what the Kon Tiki crew recorded.

Altimetry in conjunction with other oceanographic measurements has advanced our knowledge of the ocean over the past 15 years. We know a lot more about currents now than in 1947, and today we can predict how they might change. Models of currents, El Niño etc. have been developed by drawing on this knowledge, and now enable navigators to choose their routes and the most suitable times for their sea crossings.

See also:

Websites on this subject:


  • Legeckis R., C.W. Brown, F. Bonjean and E.S. Johnson, 2004. Satellites reveal the influence of equatorial currents and tropical instability waves on the drift of the Kon-Tiki in the Pacific, Oceanography I, Vol.17, No.4, Dec. 2004.
  • Legeckis, Richard; Brown, Christopher W.; Bonjean, Fabrice; Johnson, Eric S., 2004. The influence of tropical instability waves on phytoplankton blooms in the wake of the Marquesas Islands during 1998 and on the currents observed during the drift of the Kon-Tiki in 1947, Geophys. Res. Lett., Vol. 31, No. 23, L2330710.1029/2004GL021637
Rss feedsContactPartnersFAQLexiconLegal noticePersonal Data Protection PolicyMobile
You must enable cookies in your browser preferences to save the modifications
You are using an older version of Internet Explorer, please update to take full advantage of Aviso+ features

Customize the home page

View all widgets
Reduce display
Public profile
User profile

Select/Deselect widgets

Discover AVISO+

Customizable home, reading tools, products search guide, etc.. Discover step by step the features of the new site AVISO+.

Customizable homepage

This home page is composed of blocks called "widgets".

Rearrange the blocks with a "Click & Drop".

Hide a widget with the cross at the top right. Reset or add a widget with the "wrench" icon. The "User" and "Public" profiles offer a predefined organization.

All the modifications are automatically saved as cookies on your machine so as to enable you to have your own specific AVISO+.

Reading tools

Ease your reading by choosing the page background colour (black/white) and/or by modifying the font size.

Browsing menu and breadcrum trail

To ease your browsing through AVISO+, you can use at any time the main banner items with the interactive submenus or use the browsing menu on the left side of the screen (it is open by default). For more readiness of the page contents, you can fold and unfold the browsing menu by clicking on the tab. At any time you can know where you are thanks to the browsing menu or the breadcrum at the top of the page.

Products search guide

The first submenu of the "Data" banner item leads you to a new search form enabling you to find quickier the product that suits your needs. The list of results is updated according to your selection criteria.

AVISO+ Multimedia

The first submenu of the "Multimedia" banner item leads you to AVISO+ collections of images and videos linked to altimetry and its applications. Have a nice visit!