Among the missing are several girls and an infant, announces Myss Belmonde Dogo, minister for cohesion and solidarity, on Facebook.
The hippopotamus is said to have tipped the long, narrow canoe-like boat when it was traveling along the Sassandra River near the town of Buyo in the southwestern part of the country.
Three of the fourteen people on board have been rescued and a search effort is underway for the rest.
Around 500 hippopotamuses are estimated to exist in Ivory Coast. Research from 2022 shows that the hippopotamus is the animal species in the country that in encounters with humans causes the most injuries and deaths.