Moko is an explorer. As he travels the world continent by continent, he makes many friends and discovers many natural phenomena which sometimes delight him, and other times scare him. Each animated episode recounts an adventure and takes an "original story" approach to explaining these natural phenomena. In this episode, continuing their expedition, Moko and Totemie come across a great river. It is so beautiful and so wide that they decide to build a raft and explore it further. A woman who is returning from the fields warns them of a great danger, but it is too late, the current has already carried the raft along its waves. In the distance they can hear a deep rumbling sound, and it seems to be getting closer. As their raft is propelled forward, it is stopped by the edge of a reef just on the edge of a great chasm. The spectacle is so breathtaking that they forget their fear. When they finally manage to reach the shore safely, they thank the river for having kept them safe and having shown them the magnificent view of the waterfall.