Two stamps with the same design were issued in 1970 by Guinea. The design shows a map of Africa with four countries shaded in color: Mali-green, Mauritania-blue, Senegal-yellow and Guinea-red.
The stamps commemorate the meeting of representatives of the countries bordering on the Senegal river, the OERS, "Organisation Etats Riverains du Senegal".
This is a more detailed map, that shows the Senegal River.
I am describing this, so you can situate the stamp that shows a canoe race on the Senegal.
It is quite a facinating event. There are plenty of stamps on the subject. I also found some old postcards with the canoes or "pirogues". I am showing some here. Click on the pictures and you will see them bigger.